STK16, also known as serine/threonine-protein kinase 16, is a membrane-associated protein kinase that phosphorylates on serine and threonine residues. STK16 may be involved in secretory vesicle trafficking or intracellular signaling. Also this protein may have a role in regulating stromal-epithelial interactions that occur during ductal morphogenesis in the mammary gland. It able to autophosphorylate on Tyr residue; it is however unclear whether it has tyrosine-protein kinase toward other proteins.