STK3 and cancer: The PI3K-AKT pathway is an essential intracellular signaling pathway associated with various cellular processes, such as cell differentiation, metabolism, inflammation, cell motility, cancer, etc. PI3K, as an important signal transduction molecule in cells, can catalyze the phosphorylation of phosphatid ylinositol-4,5-bisphosphate (PIP2) at the 3-hydroxy position to form PIP3, which acts as a second messenger to recruit 3-phosphoinositide-dependent protein kinase 1 (PDK 1) and serine/threonine kinase 3 (AKT) onto the cell membrane.