To investigate the involvement of PTHrP in primary BC initiation and progression, we generated a mammary epithelial-specific Pthrp-knockout (Pthrpflox/flox; Cre+) in a transgenic BC mouse model (PyMT) which Cre specifically expressed in mammary epithelium is monitored by membrane-targeted GFP (mT/mG reporter). The gene discussed is PTHLH; the disease is breast cancer.