ABCB1 and cancer: Although little is known about the signalling pathways targeted by the HIV-PIs in general, and how these pathways regulate ABCB1 in particular, previous reports found that nelfinavir treatment decreased signalling through the PI3K/Akt pathway (Gupta et al, 2007), a regulator of cellular proliferation and survival in human cancer cells including KS (Vivanco and Sawyers, 2002; Chaisuparat et al, 2008).