PIK3CA and cancer: Our results indicated that the phosphorylation status of AKT on Thr308 and Ser473 and the phosphorylation levels of AKT downstream targets (FKHRL1 and GSK-3β) were much higher in SP cells than those in NSP cells (Figure 2A), suggesting that the PI3K/AKT pathway was activated in NPC cancer stem-like SP cells.