STC2 accumulation increases in pancreatic tissue following induction of pancreatic injury. (A, B) Immunofluorescence (IF) for pPERK (green) before (A) and 4 hours after (B) initiation of CIP. pPERK (arrowhead) localizes to the apical end of acinar cells under physiological conditions and more basally during CIP. Magnification bar = 13 μM. DAPI was used to counter stain nuclei. (C) RT-PCR of whole pancreatic RNA extracts from saline (S) and cerulein (C) treated mice showed increased accumulation of Stc2 and Atf3 mRNA after initiation of CIP in pancreatic tissue. Amplification of Amylase (Amy) was used as a positive control for RT reactions. (D) Northern blot analysis revealed elevated Stc2 mRNA four hours after initial cerulein (CIP) or saline (S) injection. No increases in Stc2 were observed in Mist1-/-(M-/-) pancreatic tissue under similar conditions. (E, F) IF for ATF3 expression revealed limited accumulation before CIP (E) and acinar-specific expression afterwards (F). Magnification bar = 63 μM. I = islet.