May play a role in the ERK signaling pathway by inhibiting the dephosphorylation of ERK by phosphatase PP2A-PPP2R5C holoenzyme. Acts also as an ERK downstream effector mediating survival. As a member of the NUPR1/RELB/IER3 survival pathway, may provide pancreatic ductal adenocarcinoma with remarkable resistance to cell stress, such as starvation or gemcitabine treatment. Interacts with the PPP2R5C-PP2A holoenzyme and ERK kinases; regulates ERK dephosphorylation. By radiation, 12-O-tetradecanoyl phorbol-13 acetate (TPA), okadaic acid, TNF and NUPR1. Phosphorylated at Thr-18, Thr-123 and Ser-126 by MAPK1/ERK2 and probably MAPK3/ERK1. Upon phosphorylation by MAPK1/ERK2 and MAPK3/ERK1, acquires the ability to inhibit cell death induced by various stimuli. Glycosylated. Belongs to the IER3 family.