Plays a role as a transcription factor. Mediates positive transcriptional regulation of several chaperone gene during the heat shock response in a HSF1-dependent manner. Mediates negative transcriptional regulation of CDC25B expression. Plays a role in the dephosphorylation of the heat shock factor HSF1 and ribosomal protein S6 kinase (S6K) by the protein phosphatase PP2A. Involved in the regulation of cell proliferation and resistance to thermal stress. Involved in the cell cycle checkpoint and survival in response to ionizing radiation. Associates with chromatin to the CDC25B promoter. Monomer. Homodimer. Associates with the catalytic subunit of protein phosphatase PP2A. Interacts (via N- and C-terminal regions) with PPP2R2B. Interacts with PPP2R2A, PPP2R2C and PPP2R2D. Interacts (via N-terminus) with RPS6KB1. Interacts (via central region) with HSF1; this interaction promotes PPP2CA-induced HSF1 dephosphorylation, leading to enhanced HSF1 transcriptional activity. Predominantly cytoplasmic. Translocated in the nucleus during heat shock. By serum and growth factors. Belongs to the IER family.