PBase stability is not influenced by DNA–PK components. (A) Ku70, Ku80, and DNA-PKcs were down-regulated by RNAi constructs miR-701, miR-801, and miR-PK2 (miR-N is a negative control) in 293T cells. PBase expression levels were detected from each line of cells. (B) PBase expression levels were detected in PIEC cells with or without DNA–PK components. Human cDNAs of Ku70, Ku80, and DNA-PKcs were all expressed in PIEC cells.