Protein tyrosine phosphatase non-receptor type 21 (PTPN21)

Protein tyrosine phosphatase non-receptor type 21 (PTPN21) is a cytosolic enzyme belonging to the protein tyrosine phosphatase family and plays a key role in the regulation of numerous cellular processes, including cell signaling, growth, differentiation, adhesion, motility, and oncogenic transformation[1][2][3][4][5][7]. PTPN21 contains an N-terminal FERM domain—which targets the protein to the cell membrane and facilitates assembly with cytoskeletal and adhesion complex proteins—and a C-terminal phosphatase domain[4][5]. The enzyme modulates signaling by interacting with partners such as BMX (a Tec tyrosine kinase) to enhance STAT3 activity as well as KIF1C to regulate vesicle transport[1][2][3]. It also regulates actin dynamics, focal adhesion formation, and Src–EGF receptor–focal adhesion kinase signaling pathways[1][4][7]. PTPN21 is implicated in oncogenic transformation and cell survival in several cancer cell types, making it an emerging therapeutic target in oncology[2][3][7]. No drugs are currently known to selectively target PTPN21, and there are no reported biomarkers for patient selection or efficacy monitoring. Caution is advised in therapeutic targeting due to its roles in both normal physiological and potentially oncogenic processes[2][7].

Other names

Tyrosine-protein phosphatase non-receptor type 21PTPD1PTPRL10Protein-tyrosine phosphatase D1dJ1175B15.2

Dephosphorylation of substrate proteins (e.g., FAK, IκB kinase β, ErbB4); Modulation of oncogenic signaling through interaction with partners such as BMX and KIF1C