PTK7 and cancer: CCK4/PTK7 was first described by Mossie et al., in 1995, and its functions are not completely understood.319 Initially named CCK-4 (colon carcinoma kinase 4), PTK7 is regulating Wnt signaling pathways and controls morphogenesis and patterning modulating cell molarity, migration and wound healing.320–322 Later, it was shown that PTK7 expression could be correlated with cancer development and metastasis, while mutations in PTK7 are involved in human neural tube closure defects, scoliosis or inner ear polarity defects.323–326