Confirming the estrogen insensitivity of the PyMT line, tamoxifen did not directly affect tumor cell proliferation in vitro (Supplementary Fig. 3B) and PyMT subcutaneous (SQ) tumor growth was reduced in tamoxifen-treated αSMA-Dkk1cKO male mice compared to controls (Supplementary Fig. 3C). Here, ACTA1 is linked to neoplasm.