RAC1 and familial pancreatic carcinoma: Overexpression/hyperactivation of RAC1 is detected in the majority of breast and pancreatic cancers particularly in the tumor stroma [59] and is generally a consequence of enhanced upstream inputs from RTKs, PI3K or guanine nucleotide exchange factors (GEFs), or reduced RAC inactivation by GTPase-activating proteins (GAPs).