Nemo-like kinase (NLK) is an evolutionarily conserved mitogen activated protein kinase-like kinase, belonging to serine/threonine protein kinase superfamily. By participating in Wnt, Notch, FoxO and other pathways, NLK can regulate cell proliferation, differentiation, morphological changes, early embryonic development of vertebrate nervous system, and other biological processes. NLK is also a key molecule in tumor regulation and its roles vary in different tumors. In prostate cancer, non-small cell lung cancer, ovarian cancer, and breast cancer, NLK plays an inhibitory role, while it plays opposite roles in oral squamous cell carcinoma, hepatocellular carcinoma, and the bile duct tumors.