Although Src activity may be increased 4- to 20-fold in breast cancer tumours as compared with normal tissues, this increase is not always accompanied by corresponding increases in Src protein expression (Rosen et al, 1986; Ottenhoff-Kalff et al, 1992; Verbeek et al, 1996; Summy and Gallick, 2003). The gene discussed is SRC; the disease is breast cancer.