ZEB1 and neoplasm: However, Zeb1 downregulation in all cells of the Zeb1(+/−) mice to around half of the levels in wild-type counterparts [referred to hereafter as Zeb1(+/+) mice] is sufficient to block ZEB1 functions in multiple systems (e.g., tumor progression, muscle wasting, muscle injury and regeneration) and cell types, including macrophages29,30,34–38.