Complex sentence: Chromosomal translocation and extra chromosomes help create abnormally high activity of certain proto-oncogenes, which caused by these genetic abnormalities and include those encoding c-myc, HRAS, and vav.
Split into simpler sentences: Chromosomal translocation and extra chromosomes help create abnormally high activity of certain proto-oncogenes. Proto-oncogenes with increased activity caused by these genetic abnormalities include those encoding c-myc, HRAS, and vav.