ACVR1B and pancreatic neoplasm: To determine whether it is possible to reprogram siCAFs in the human setting, we performed in vitro coculture of human CAFs with human pancreatic cancer cell line PANC-1 cells, a human PDAC cell line previously described to express ALK4 (24) and respond to activin A (25), in the presence or absence of ActRIIBFc.