Raymond L. Erikson, PhD: In Memoriam (1936–2020)
Authors: David A. Alcorta
Journal: Cancer Research (2020)

In 2016, Ray started a personal reflection on his career in science titled “Four Decades of Protein Phosphorylation and Cancer Research.” Nothing more aptly fit his midwestern philosophy than earnest work—if done hard and right, and if necessary, long, will generate beautiful flowers, be it in the garden or in scientific research. On March 30, 2020, the scientific community lost one of its early pioneers in oncogene research and in the development of the modern field of signal transduction. His identification of the avian sarcoma virus (AVS) Src protein as a transforming agent and its characterization as a kinase were pivotal in spurring the investigation of how reversible protein phosphorylation regulated a myriad of cellular pathways. His influence reaches beyond this transformational work through training of doctoral students and intellectual interactions with his postdoctoral fellows and colleagues, which ripples through multiple generations of scientists. He died of complications of bladder cancer at the age of 84 in his Cambridge, MA, home. He was a professor emeritus in the Department of Molecular and Cellular Biology at Harvard University (Cambridge, MA).Ray was born outside of Eagle, WI, in 1936 on a dairy farm settled by his grandfather and father and then passed down to his younger brother, Gordon, who still manages its operation. His early schooling took place in a one-room schoolhouse. Ray enrolled at University of Wisconsin (Madison, WI) with the full support and encouragement of his parents, neither of them high school graduates. This parental support, as he noted in his reflections, was unusual for the times. His initial ambitions stretched only to an undergraduate degree and then to teach agricultural science in high school. But in his junior year, he enrolled in Dr. James Crow's genetics course and Professor Crow's clear and informative lectures excited him. Dr. Crow encouraged him to read and understand the original research literature. These lectures and readings changed the way Ray viewed his educational and vocational possibilities.Following his graduation in 1958, he enrolled in the University's graduate school, entering the newly established Cellular and Molecular Biology program. Working in the laboratory of Dr. Waclaw Szybalski, he earned his PhD in 1963 on the radiation sensitivity of human cell lines. Equally important, during this period he met his first wife, Eleanor (Jo) Erikson. Jo was a key research member of his laboratory during the seminal work on Src at the University of Colorado Medical Center (Denver, CO). Ray and Jo divorced but remained life-long friends and colleagues. His postdoctoral fellowship in Dr. Richard Franklin's laboratory led to his move from Madison to Denver where he worked on RNA bacteriophages. This work led to an independent faculty appointment there and he began studies on picornaviruses and RNA tumor viruses, exploring the mechanism of virus replication and the RNAs generated. Following promotion to full professor in 1972, Ray took a sabbatical year at the Imperial Cancer Research Fund, where he had extensive and enjoyable discussions with Alan Bernstein, Steve Martin, Robin Weiss, and John Wyke on the ASV transformation of cells. He returned to Denver with a newfound interest in understanding how ASV, a single-stranded RNA virus, caused this transformation.At the time, Hidesaburo Hanafusa and others had identified and isolated strains of ASV that were transformation defective (td) and temperature sensitive (ts), showing separation of the replication and transforming activity of the virus. Ray reasoned that (i) cell-free in vitro translation of proteins from viral RNAs from these different ts and td strains might identify transformation-specific proteins by their absence in td RNAs, and (ii) alternatively or in combination, identification of the transforming protein could be done using the already proven methodology used for polyomavirus and SV40 DNA tumor viruses of generating viral-specific antibodies through tumor induction in animals.In 1974, Tony Purchio joined the laboratory as a graduate student and, working with Jo Erikson, began work on isolating the viral RNAs from wild-type (wt) and td viruses and setting up a sensitive and reliable in vitro translation system. These studies on translated viral RNAs identified a 60 kDa protein as the putative transforming protein. Joan Brugge who had joined the laboratory in 1975 developed the complementary approach of antibody-specific reagents. In experiments utilizing antisera from tumor-bearing rabbits (TBR), she identified a transformation-specific 60 kDa protein in ASV-transformed cells. But the crucial result was that the peptide mapping of proteolytic fragments of both proteins showed the in vitro and in vivo p60 proteins to be identical, eliminating the possibility that p60 was a cellular protein. Previously identified as a phosphoprotein, they called it pp60src. This result confirmed pp60src as the transforming agent in ASV and the results were published in early 1978. The culprit had been identified but its means of action were not yet known.The work was not without heated competition as J. Michael Bishop and Harold Varmus at the University of California San Francisco (San Francisco, CA), using ASV transformation–specific probes, had reported a cellular counterpart of Src in humans. Furthermore, Ray had generously provided TBR sera to multiple laboratories who had replicated his results and could scoop him. Purchio moved on to do postdoctoral studies and Marc Collett joined the laboratory. At an in-house seminar, Ray presented this data and based upon its low abundance, and being a phosphoprotein, stated they believed that Src was a kinase. Tom Langan, Professor of Pharmacology rebuked him for what he viewed as a naïve statement without supporting data and stated “If you think it is a protein kinase, I suggest that you do a direct experiment.” Humbled, and wondering the best way to approach this, within days, Ray found that Collett had taken on this challenge and performed a series of phosphorylation assays on the classic kinase substrates, histone and casein, with radiolabeled 32P-ATP and immunoprecipitated pp60src from transformed cells. Separated on gels, he found no phosphate incorporated into either but strong 32P incorporation into IgG of the precipitating antibody. This immune complex kinase assay was a novel approach for testing functionality. Replicating the experiment with in vitro–translated viral RNAs showed similar kinase activity, thus excluding the possibility of an associated cellular protein. pp60src was a kinase. To identify the phosphorylated amino acid(s), paper chromatography at pH 1.9 of hydrolyzed IgGs separated the then known amino acid phosphorylation sites of phosphoserine and phosphothreonine (p-thr). An apparent p-thr spot was observed. In their 1978 report, Collett and Erikson detailed that the transforming activity of pp60src was due to its kinase activity.Based upon Bishop and Varmus' data showing v-Src contained a transduced human Src gene, Ray was surprised that no kinase activity was found in untransformed cells using his TBR sera, but after receiving marmoset sera from tumor-bearing animals, he identified a similar Src-like kinase activity there as did other laboratories with other reagents. Furthermore, use of the immune complex enzyme assay to reveal kinase and phosphatase activity of the precipitated proteins was adopted by many laboratories and quickly resulted in, among other proteins, the identification of the EGFR and the mos oncogene as kinases.But an important coda on the Src kinase activity story still remained. Tony Hunter and Bart Sefton, investigating the transforming proteins of polyomavirus middle-T (mT) antigen and ASV, confirmed v-Src kinase activity and identified a middle-T–associated kinase activity, later identified by Sarah Courtneidge as mT bound cellular Src. But, in an often-told tale, Hunter's “pH 1.9” chromatography of hydrolysates from both mT- and ASV-phosphorylated IgGs showed a mysterious spot not coincident with p-thr. Reuse of the chromatography buffer, a practice in Ray's laboratory that would have been met with a stern look, a harrumph and quiet instructions to repeat, had resulted in a buffer pH change to 1.7, leading to separation of the distinct not-p-thr spot. Aware that tyrosine was also capable of phosphorylation, Hunter and colleagues utilized different chromatographic methods to separate the three phosphoamino acids and showed the mystery spot was phosphotyrosine (p-tyr). Viral Src and the mT-associated kinase phosphorylated tyrosine, a previously unknown site of phosphorylation.The importance and implications of Ray's work on Src was immediately recognized by the scientific community and garnered many awards, among them the Robert Koch Prize (1982), the Alfred P. Sloan Jr Prize (1983), and the Lasker award for Biomedical Research Award (1982), which he shared with Robert Gallo, J. Michael Bishop, Harold Varmus, and Hidesaboro Hanafusa. Through their interactions at this time, Ray and Hanafusa formed a close, life-long friendship that lasted until Hanafusa's death in 2009. Ray was elected into the National Academy of Science (1982) and the American Academy of Arts and Sciences (1984).With a move to the predecessor of the Molecular and Cellular Biology Department at Harvard in 1982, the focus of his now greatly enlarged laboratory group was on detailing the downstream pathways altered by v-Src and cellular proteins induced by growth factors and v-Src's transforming activity. His productivity and innovation did not lag. There is insufficient space here to properly credit the researchers and detail their fine work, but over the next decade, his group characterized and/or cloned the well-known signaling kinases, S6K, Rsk, and MEK and the phosphatase PTP-1B. Two studies, published in 1991 and 1992, are worth noting for lasting implications. In work initiated in Ray's laboratory, Dan Simmons and Dan Levy cloned a mitogen and v-Src–induced gene, CEF-147. The Simmons' laboratory then showed it to be a novel form of the prostaglandin synthase, the cyclooxygenase 2 (COX2) gene. They extensively characterized the gene that was instrumental in the development of pharmacologic COX2-specific inhibitors soon after. In the second study, Dan Simmons, Ben Neel, and Ray cloned an early response kinase they termed serum-inducible gene, snk. Snk was identified as member of the polo-like kinase family and Ray continued to characterize its function in the years before his retirement. His work showed its importance in centriolar organization, chromosome segregation, and the DNA damage response in cells. In a scientific career spanning 1963–2017, he was a contributor to over 190 publications.In training graduate students and mentoring postdoctoral fellows, Ray viewed providing guidance and support as his primary role. Dan Simmons summed it up well, “Ray fostered a spirit of collegiality and the highest standards of scientific inquiry among his research team.” He did not require specific work hours but was quick to remind, “it is your career” when it came to results. He expected earnest intellectual contributions in laboratory meetings, civil laboratory manners, and involvement in a range of laboratory maintenance chores, including a laboratory rite of passage, making frequently required labeled ATP for kinase assays from 25–50 mCu of 32P phosphate each time, and if you defaulted on any of these responsibilities, as happened on rare occasion, “alternate arrangements were made.” With such a diverse and driven group of students and postdocs, the laboratory was a vibrant and exciting place where doing good science was the most important thing. During my time in his laboratory, I never once heard Ray raise his voice, not to say there were not energetic discussions and significant disagreements, but we came to understand the meaning of “what part of no do not you understand,” the expression of which Donna, his wife of 31 years, recently reminded me, he would calmly invoke. But most of all, Ray loved to do, discuss, and explore science, and that philosophy was instilled and/or reinforced in all that joined the laboratory.Beyond the laboratory, Ray enriched the personal lives of all he knew by sharing his love of art, music, fine food, fine cars, and travel. He frequently hosted laboratory dinners at his Cambridge home, cooking the main courses, pouring the wine, and on at least one occasion I remember him tolerating rock music blasting out of his expensive stereo as his postdocs danced around his front room late into the night. Ray's love of Sante Fe and Taos showed in the paintings, photos, and sculptures from the region and he happily discussed the heritage and culture revealed in them. His wife, Donna, was an equal and guiding partner for all of these events.His personal friendships with folks from all walks of life highlighted his quiet humor, the depth of his intellectual curiosity, his unflagging loyalty, and his humility. In his honor, the Raymond Leo Erikson Professor of Life Sciences endowed chair has been established at Harvard. He was a great scientist but a better husband and father to his family, and a friend to all who knew him. He will be truly missed.