Serine/threonine-protein phosphatase 2A, commonly known as Protein Phosphatase 2A (PP2A), is a highly conserved and ubiquitous Ser/Thr protein phosphatase found in eukaryotic organisms. It plays a pivotal role in various cellular processes such as cell cycle, metabolism, migration, and apoptosis. PP2A consists of a catalytic subunit C, a structural subunit A, and variable regulatory subunits B, with the catalytic subunit C (PP2A/C) serving as the core of its enzymatic activity and functionality. Specifically, PP2A regulates numerous cellular functions by catalyzing the dephosphorylation of proteins. Dephosphorylation is a crucial step in many cellular signaling pathways, affecting protein activity and function. Therefore, PP2A is instrumental in regulating cell proliferation, differentiation, apoptosis, and responses to external stimuli. Moreover, PP2A has close ties with the immune system. For instance, the activity of PP2A is significantly elevated in Treg cells (Regulatory T cells), and its high expression is essential for Treg cells to maintain their immunosuppressive function. This indicates that PP2A plays a crucial role in regulating immune responses and maintaining immune homeostasis.