PTK7 and breast carcinoma: For example, evidence shows that the conserved biomarker transmembrane protein tyrosine kinase 7 (PTK7), a pseudokinase family of receptor tyrosine kinases family member, is overexpressed in colon cancer, breast cancer, lung cancer, and esophageal cancer compared with that in normal tissues, and has vital functions in tumorigenesis and progression [22–26].