Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Ex Input:
Context: Neural stem/progenitor cells (NSCs) reside in the subventricular zone (SVZ) and subgranular zone of the hippocampal dentate gyrus in adult mammals. The ubiquitin ligase HRD1 is associated with degradation of amyloid precursor protein and believed to be specifically expressed in neurons and not in astrocytes. We investigated expression of HRD1 using immunohistochemistry and found colocalization of HRD1 with the NSC marker protein nestin and glial fibrillary acidic protein in the NSCs of the SVZ (the SVZ astrocytes) but not in the hippocampus. In the hippocampal dentate gyrus, HRD1 is localized in the nucleus of nestin-positive cells. 
 Question: Which intermediate filament (IF) protein can be used as a non-specific marker of the neuronal precursor cells of the subventricular zone?

Ex Output:
nestin


Ex Input:
Context: Rachel (Andrea Bowen), a high school girl, seems to have the life that most people envy: she has a steady boyfriend, some great friends, and a place on the school's soccer team. Preparing for college and separating from her boyfriend are the main worries of this teen, as she lives a carefree life like most girls her age. However, Rachel's world falls apart the day she discovers that Jason (Eric von Detton), a former sexual partner of hers that died an untimely death, was in fact HIV positive and an IV drug user. She immediately goes to an AIDS clinic to get a rapid test, which unfortunately comes back positive. Devastated by the fact that she may actually be infected with the virus, Rachel then confides in her substitute teacher, Sarah (Jennie Garth), who has secretly been living with the disease for years. But both young women are about to find out their secrets will not be kept secret for very long, as word begins to spread throughout their high school and rumors fly, making some of these students realize that they may not be as "clean" as they think they are. 
 Question: What were the results of Rachel's rapid test at the AIDS clinic?

Ex Output:
positive


Ex Input:
Context: One of the colors of mink is Aleutian (aa)-a specific gun-metal gray pigmentation of the fur-commonly used in combination with other color loci to generate popular colors such as Violet (aammpp) and Sapphire (aapp). The Aleutian color allele is a manifestation of mink Chediak-Higashi syndrome (CHS), which has been described in humans and several other species. As with forms of CHS in other species, we report that the mink CHS is linked to the lysosomal trafficking regulator ( LYST ) gene. Furthermore, we have identified a base deletion (c.9468delC) in exon 40 of LYST, which causes a frameshift and virtually terminates the LYST product prematurely (p.Leu3156Phefs*37). We investigated the blood parameters of three wild-type mink and three CHS mink. No difference in the platelet number between the two groups was observed, but an accumulation of platelets between the groups appears different when collagen is used as a coagulant. Microscopic analysis of peripheral blood indicates giant inclusions in the neutrophils of the Aleutian mink types. Molecular findings at the LYST locus enable the development of genetic tests for analyzing the color selection in American mink. 
 Question: Which mutated gene causes the ChediakHigashi Syndrome?

Ex Output:

lysosomal trafficking regulator gene