MAPK3 and breast cancer: Interaction of Src with numerous breast cancer-associated growth factors and signalling pathways, such as prolactin (Acosta et al, 2003), EGFR (Biscardi et al, 2000), ERK1/2, PI3-kinase (Gaben et al, 2004), and oestrogen receptor (Migliaccio et al, 2005), supports the notion that Src activity contributes to the growth and survival of breast cancer cells.