To strengthen our hypothesis that any cell with a single oncosuppressor mutation might be susceptible to integrate mutating factors at metastatic sites, we generated a human fibroblast cell line deficient for the oncosuppressor BRCA1 (Breast cancer susceptibility gene 1) using the CRISPR technology and we exposed it to different types of patients’ cancer sera and healthy patients’ sera. Here, BRCA1 is linked to cancer.