Thus, our and previous findings support ZEB1 as a strong candidate tumor suppressor gene in CTCL as already described in ATLL;20 differently from canonical cancer genes like TP53, PTEN, RB1, and CDKN2A recurrently inactivated also in other cancer types, ZEB1 seems to be a lineage-specific tumor suppressor. Here, RB1 is linked to adult T-cell leukemia/lymphoma.