Basal cells in the breast are positive for “basal cell markers” (karatin 14 and smooth muscle).
Howard BA, Gusterson BA. 2000. Human breast development. Journal of Mammary Gland Biology and Neoplasia 5(2):119-137.
Two cell populations can be distinguished in the epithelium: the inner luminal cell population which is separated from the basement membrane by an outer basal (myoepithielial) layer. The epidermal transforming growth factor TGFα is highly expressed, suggesting proliferation.
Howard BA, Gusterson BA. 2000. Human breast development. Journal of Mammary Gland Biology and Neoplasia 5(2):119-137.