Figure 2.

Phosphoinositide 3-kinase (PI3K) signalling and cancer. Schematic signalling pathway indicating the interactions that occur between known breast cancer oncogenes (ErbB2, Src) and tumour suppressors (PTEN, BRCA1) with components of the PI3K signalling cassette. Direct physical interactions are shown with solid arrows. Processes involving several steps are indicated with a dashed arrow; +, an activation step. Blunt arrows indicate inhibitory effects. Akt, Protein kinase B; ATM, ataxia telangiectasia mutated; ER, oestrogen receptor; 3-Ptase and 5-Ptase, phosphoinositide 3-phosphatase and phosphoinositide 5-phosphatase activities; PTEN, phosphatase and tensin homolog deleted on chromosome 10; TOR, target of rapamycin.