Also, in a murine model of spontaneous metastasis involving 4T1 breast adenocarcinoma in immune-competent BALB/c mice, the genetic deletion of Crk via CRISPR-Cas9 technology resulted in an increase in populations of anti-tumor immune cells, as well as elevated levels of cytotoxic effector cells and immune surveillance cytokines within the primary tumor. This evidence concerns the gene CRK and neoplasm.