TOPK (T-LAK cell-originated protein kinase), also known as PDZ-binding kinase, is a protein kinase activated by mitogen-activated protein kinase (MAPK). It comprises a kinase domain and predominantly localizes in the cytoplasm and nucleus, regulating processes such as the cell cycle, cell division, and DNA damage response. TOPK is expressed in various tissues, with significantly elevated levels observed, particularly in highly proliferative tissues and certain cancer cells. Mutations and overexpression of the gene are closely associated with tumorigenesis and progression. It participates in multiple signaling pathways, including MAPK, PI3K/Akt, to regulate cell proliferation, differentiation, and survival.