The G0/G1 switch gene 2 (G0S2) is a protein of about 103 amino acids that was first discovered in mononuclear blood cells, where it was initially believed to unblock cells from the G0 to the G1 phase, although it was later recognized that it does the opposite: maintaining cells in a quiescent state, acting as a tumor suppressor gene in cancer, and regulating adipogenesis [31]. The gene discussed is G0S2; the disease is cancer.