FIG. 8.

Schematic illustrating how MIST1 expression is induced as mucous neck cells differentiate into zymogenic cells. MIST1 is modeled as acting primarily through RAB3D and RAB26 to regulate large zymogenic granules, though a role for other MIST1 targets in this process has not necessarily been ruled out. Other targets of MIST1 are probably involved in the apical-basal cell shape reorganization induced by MIST1. Based on an earlier study, the cytoskeletal adaptor CD2AP plays a role in this process but is not a target of MIST1 (5). Expansion of rER is not affected by loss of MIST1 expression.