MUC5AC and neoplasm: Similarly, MUC4 but not MUC5AC was found to be overexpressed in the majority of early PanINs in a human pancreatic specimen, which predominantly consisted of small‐sized PanINs suggestive of early‐stage lesions (Figure S6, Supporting Information), as well as in stage I/II of PDAC tumor specimens (Figure S7, Supporting Information).