MUC5AC and neoplasm: In keeping with previous studies (Hingorani et al, 2003; Tuveson et al, 2004), analysis of pancreatic sections from 6- to 12-mo-old KC mice stained with hematoxylin and eosin (H&E) or immunostained with antibodies to the ductal marker Cytokeratin 19 (CK19) or Mucin 5Ac (Muc5Ac) showed the presence of various tumor lesions, including PanIN-1, PanIN-2, and PanIN-3 as well as full-blown PDAC (Fig S1A).