PLK1 and osteosarcoma: The overexpressed kinases in osteosarcoma, liposarcoma, and leiomyosarcoma are mainly serine/threonine kinases (BUB1, CKD4, HUNK, LKKK1, NEK2, PBK, PLK1, and PLK4), whereas TTK has a dual role (Tyrosine and serine/threonine kinase) and only MELK presents tyrosine phosphorylation activity.