ERBB2 and breast cancer: Interestingly, in contrast to PtenΔf,p53Δf and Her2/Neu tumor cells, which contained a prominentCD24+:CD49f+ double-positive cell fraction, mostPtenΔf:p53Δf mammary tumor cells expressed low levels of theluminal marker CD24 and were CD24−:CD49f− orCD24−:CD49f+ (Fig4A andB).