SHH and Patent ductus arteriosus: While Smo deletion in the pancreatic epithelium has no effect on mutant KRAS-driven PDA in GEM models, studies from our group and others reveal a surprising role for SHH in restraining cancer growth (Lee et al., 2014; Mathew et al., 2014; Rhim et al., 2014; Liu et al., 2016).