PER1 and lung cancer: In A549 lung cancer cells, a very low expression level of phosphorylated PI3-K (p-PI3-K) was observed in the Wor+T4 (at 0 h), Per+T4 (at 24 h), and Rap+T4 (at 24 h) groups; no expression of p-PI3-K was observed in the Wor+T4 group at 24 h; and the expression levels of p-PI3-K in the Per+T4 and Rap+T4 groups at 0 h were not significantly different than that of the control.