RAC1 is a member of the Rho family and is a GTPase that is part of the small GTP-binding protein superfamily. RAC1 is involved in a diverse array of cellular events, including the control of cell growth, cytoskeletal reorganization, and the activation of protein kinases. Role of RAC1 in colorectal cancer has been reported after analysis of the protein expression level and activities of this protein in matched sets of tumor and non-tumor tissues. Overexpression of RAC1 leads to increased tumour growth in xenografts of human colorectal tumour cells. RAC1 is also involved in the regulation of critical cellular functions including organization of actin cytoskeleton, transcription control and cell cycle.