ZEB1 and cancer: Moreover, direct contact between EMT-PDAC cells and myofibroblasts stimulates the secretion of activin A. Activin A promotes the initiation of the EMT program (upregulating the expression of Snail and ZEB1) and the differentiation of myofibroblasts in neighboring cancer cells in a paracrine pattern; on the other hand, it promotes the secretion of activin A by actin alpha 2 (ACTA2) in myofibroblasts in an autocrine pattern [8].