H-Ras p21 oncogene protein, molecular model. The Ras proteins are involved in transmitting signals within cells. Excessive signalling can lead to conditions such as cancer, and this protein is hence classed as an oncogene protein. H-Ras (HRAS) is also known as transforming protein p21. It plays a role in regulating cell division in response to growth factor stimulation, and also in GTP synthesis (the production of guanosine triphosphate). Ras inhibitors are being studied as a treatment for cancer.