In this model, CAFs secreted high levels of CXCL12 which induced endothelial progenitor cell recruitment.108 Moreover, PyMT CAFs embedded in matrigel plugs subcutaneously transplanted induced vascularization of the plug, and silencing of YAP1 decreased this pro‐angiogenic capacity.52 Stromal deletion of the tumor suppressor Pten promoted angiogenesis and tumorigenesis in MMTV‐ErbB2/neu and MMTV‐PyMT breast cancer models. This evidence concerns the gene ERBB2 and breast cancer.