PTH1R and invasive ductal breast carcinoma: In another murine study (36), involving transgenic mice that synthesize the large T antigen under the control of the whey acidic protein promoter–TNP8 mice resulting in multifocal ductal carcinoma in situ and, ultimately, invasive ductal breast carcinoma (IDC), Pth1r levels were significantly lower in IDC than in breast tissue from WT nonlactating mice (Figure 3A).