We set out to develop an in vivo model to address the role of the SWI/SNF component ARID1A in pancreatic ductal adenocarcinoma (PDAC), a setting in which mutations in ARID1A or other SWI/SNF components occur in up to 25% of cancer patients (Shain et al., 2012). Here, SMARCA1 is linked to pancreatic ductal adenocarcinoma.