GTPase HRas, from "Harvey Rat sarcoma virus", also known as transforming protein p21 is an enzyme that in humans is encoded by the HRAS gene. The HRAS gene is located on the short (p) arm of chromosome 11 at position 15.5, from base pair 522,241 to base pair 525,549. HRas is a small G protein in the Ras subfamily of the Ras superfamily of small GTPases. Once bound to Guanosine triphosphate, H-Ras will activate a Raf kinase like c-Raf, the next step in the MAPK/ERK pathway.