Examples discussed in this review include Cdc42, Rac1, RhoA, RhoC and RhoH activation of oncogenic STAT3, and in some cases STAT5, in a range of cancers including but not limited to: breast, bladder, gastric, cervical, myeloid, pancreatic, hepatocellular, head and neck, and colorectal cancer. The gene discussed is STAT5B; the disease is cancer.