Pancreatic cysts induced by Lkb1 inhibition evolve into structures that resemble precancerous PanIN lesions. (A) E16.5 pancreatic explants were cultured on transwell filters for 8 DIV with 1 µM 1NMPP1. Lkb1^MG/MG explants developed cysts that then evolved into highly invaginated epithelial structures composed of pseudostratified columnar cells. (B) Lkb1^WT/MG explants were unaffected by the 1NMPP1 and retained their branched network of differentiating ductal and acinar cells. Tissues were fixed and processed for whole-mount confocal microscopy using Alexa Fluor 488 anti-EpCAM antibody, Alexa Fluor 546 phalloidin, and DAPI. (C) Lkb1^MG/MG explants treated with 1NMPP1 dramatically overexpress CD44 as shown in whole-mount immunofluorescence (left) using anti-CD44 antibody (clone IM7) and in Western blots (right) of explant lysates probed with anti-CD44v6 antibody (clone 9A4). Bars: (A and B) 50 µm; (C) 100 µm.