In prostate cancer cells, PI-3 kinase and p44/p42 MAPK were shown to be important for SDF-1-α-mediated invasion (Chinni et al, 2006), whereas in breast cancer cells PI-3K, but not p44/p42 MAPK, was required (Fernandis et al, 2004). The gene discussed is CXCL12; the disease is prostate carcinoma.