PTHLH and neoplasm: Consistent with prior literature [28, 73, 74], we found low levels of Pth1r expression in non-transformed HC11 mouse mammary epithelial cells or in the MECs derived from Tet-PTHrP mice, but found increased levels of Pth1r expressed in PyMT tumor cells derived from either MMTV-PyMT mice or from Tet-PTHrP;PyMT mice (Fig. 8A).