Recruits the serine/threonine-protein phosphatase PPP1CA to prevents excessive phosphorylation of the translation initiation factor eIF-2A/EIF2S1, thereby reversing the shut-off of protein synthesis initiated by stress-inducible kinases and facilitating recovery of cells from stress (PubMed:11381086, PubMed:12824288). Down-regulates the TGF-beta signaling pathway by promoting dephosphorylation of TGFB1 by PP1 (By similarity). May promote apoptosis by inducing TP53 phosphorylation on 'Ser-15' (By similarity). Plays an essential role in autophagy by tuning translation during starvation, thus enabling lysosomal biogenesis and a sustained autophagic flux (By similarity). Acts also a viral restriction factor by attenuating vesicular stomatitis virus (VSV) replication (PubMed:17670836). Interacts with PPP1CA (PubMed:9023344, PubMed:11381086). Interacts with EIF2S1 (By similarity). Interacts with PCNA (PubMed:9371605). Interacts with LYN and KMT2A/MLL1 (PubMed:11517336). Interacts with PPP1R1A and SMARCB1. Interacts with SMAD7. Interacts with BAG1. Interacts with NOX4 (By similarity). Associates with membranes via an N-terminal amphipathic intramembrane region. Expressed strongly in spleen and lung, moderately in thymus and muscle, and weakly in brain. Expression starts at 8.5 dpc, and decreases to undetectable levels at 10.5 dpc and 11.5 dpc. Expression is strongly up-regulated at 12.5 dpc, decreases at 16.5 dpc and reappears at 18.5 dpc. At 12.5 dpc, ubiquitously expressed, with high levels in brain, spinal cord, tongue, lung and genital tubercle. Specifically produced in response to stress: in absence of stress, some upstream open reading frame (uORF) of this transcript is translated, thereby preventing its translation (PubMed:19131336). By IL6 and various endoplasmic stresses such as methyl methanesulfonate (PubMed:12606582, PubMed:12824288, PubMed:8139541). (Microbial infection) By infection with various viruses such as vesicular stomatitis virus (VSV). Phosphorylated at multiple Ser/Thr residues. Phosphorylated on tyrosine by LYN; which impairs its antiproliferative activity. Phosphorylation at Tyr-239 enhances proteasomal degradation, this position is dephosphorylated by PTPN2. Polyubiquitinated. Exhibits a rapid proteasomal degradation with a half-life under 1 hour, ubiquitination depends on endoplasmic reticulum association. Mice display abnormal erythrocytes and reduced hemoglobin content due to defects in hemoglobin synthesis. Belongs to the PPP1R15 family.