KRas serves a molecular switch cycling between inactive (GDP -bound) and active (GTP -bound) states to transduce upstream cellular signals received from multiple tyrosine kinases to downstream effectors to regulate a wide variety of processes, including cellular proliferation.Kirsten Rat Sarcoma 2 Viral Oncogene Homolog (KRas) is a small GTPase and a member of the Ras family of oncogenes.