Retrovirus-associated DNA sequences (v-sis) originally isolated from the simian sarcoma virus (SSV). The proto-oncogene c-sis codes for a growth factor which is the B chain of PLATELET-DERIVED GROWTH FACTOR. v-sis or overexpression of c-sis causes tumorigenesis. The human sis gene is located at 22q12.3-13.1 on the long arm of chromosome 22.
