Of particular note is the fact that letrozole also reduced the growth of HER2-amplified BT474 A3 cells in vitro, in keeping with previous clinical observations that HER2+ breast cancer seems to be more sensitive to oestrogen deprivation than to tamoxifen (Ellis et al, 2001; Dowsett et al, 2005). The gene discussed is ERBB2; the disease is breast cancer.