This finding implicates Zeb1 as a putative tumor suppressor of several pathogenic processes in CTCL and suggests that in patients in whom the ZEB1 gene is not mutated, tumor suppressive functions of the Zeb1 protein may instead be impeded by other mechanisms such as epigenetic modification of its target DNA. The gene discussed is ZEB1; the disease is primary cutaneous T-cell non-Hodgkin lymphoma.