Tax also controls the function of cyclin-CDK complexes through the inhibition of CDK4 inhibitors including p15, p16, p18 and p19 to facilitate S phase entry and cell proliferation, and genetic alterations in these genes have been identified in ATLL [193,194,195,196,197,198,199]. The gene discussed is CNTN2; the disease is adult T-cell leukemia/lymphoma.