CAFs can stimulate CCA growth through the release of short-range and direct morphogenetic signals such as Notch [131] or Sonic Hedgehog (SHH) [132], as well as via the secretion of several factors including HGF, PDGF-BB, HB-EGF and SDF-1 [123,133,134]. The gene discussed is CXCL12; the disease is cholangiocarcinoma.