Bicistronic constructs incorporating the 5′UTRs of c-Myc, HIF-1α, VEGF or XIAP were transfected into the various cell types. The ratios of IRES/cap activities were analyzed under standard growth conditions for the various cells. (A, B, C) For c-Myc, HIF-1α and VEGF, the IRES/cap ratios were represented by FFL/SPL activity (pRF = vector control). (D) For XIAP, the IRES/cap ratio was represented by chloramphenicol acetyl transferase (CAT)/β-galactosidase activity (β-gal = vector control). Error bars represent the SD of duplicate samples. (E) Differential effects of rapamycin treatment on translation of proteins subject to both cap and IRES-translation, in K, E, L, and BP cells. ERK2 served as a gel loading control. Representative western analysis is shown. (V = vehicle)