The activities of the wild type HTLV-I LTR (CR-CAT) and the CMV promoter construct (pIEP1-CAT) in the presence and absence of rapamycin are illustrated. CAT acetylation values are given as the percentage of the rapamycin-negative control for each construct. Mean values of three independent assays are illustrated ± SEM (A). Levels of c-Myb protein from cells grown in the presence and absence of rapamycin, as detected in a western blot, are shown. A representative blot of a duplicate experiment is shown (B).