SNAI1 and neoplasm: Another TGF superfamily member, Nodal, has recently been shown to be positively correlated with alpha-smooth muscle actin (α-SMA) expression in CRC tissues, which can be secreted by tumor cells and promotes the transformation of normal fibroblasts into CAFs through the activation of the TGF-β/Smad/Snail pathway, thereby promoting CRC cell proliferation (Li et al., 2019).