PTK7 upregulation was detected in gastric, esophageal, colorectal, lung carcinoma or BC, while a downregulation of PTK7 was related to lung SCC, ovarian cancer and melanomas.327–330 Other studies underlined PTK7 role as a marker for normal colon stem cells and its potential role as a marker for tumor initiating cells in NSCLC, ovarian cancer or TNBC,331,332 while PTK7 inhibition showed a sustained tumor regression, indicating that some anti PTK7 therapies may have a role in tumor inhibition.333,334 However, no mutations have been reported to be responsible for tumor development. This evidence concerns the gene PTK7 and breast cancer.