Our previous studies have shown that Antrodia camphorata (AC), an indigenous medicinal mushroom, promoted cell-cycle arrest and apoptosis in human estrogen-responsive MCF-7 and estrogen-nonresponsive MDA-MB-231 breast cancer cells in vitro and in vivo and that both of these cell lines express basal levels of HER-2/neu [13–16, 23]. This evidence concerns the gene ERBB2 and breast cancer.