BAG-1 is expressed in most normal human tissues (Takayama et al, 1998), and its overexpression has been described not only in breast cancer, but also in other human malignancies including squamous cell carcinoma of the head and neck (Shindoh et al, 2000), chronic lymphocytic leukaemia (Kitada et al, 1998) and prostate cancer (Maki et al, 2007), in which it is associated with a poor prognosis. This evidence concerns the gene BAG1 and breast cancer.