RHO and cancer: In addition to the canonical SMAD‐dependent pathway, TGF‐β can also induce non‐SMAD pathways, including those mediated by ERK, JNK, p38 MAPK, IKK, PI3K‐AKT, and the Rho family GTPases.40 Increasing evidence demonstrates that non‐SMAD ERK signaling is associated with TGF‐β1 signaling in cancer progression.41 The details of the TGF‐β/ERK1/2 signaling pathways differ by cell types and tissues.