ACTA1 and neoplasm: Consistent with some types of human in situ lesions, indolent lesions in our model were comprised primarily of cuboidal-shaped luminal (CK8+) tumor cells, relatively uniform in appearance throughout the lesion cross-section, with a single discontinuous layer of basal (CK5+) and myoepithelial (α-SMA) cells in the surrounding basal compartment34,35.