Persistent telomerase inhibition is not associated with apoptosis but induces senescence in HTLV-I–infected cells. (A) Western blot analysis for expression of apoptosis regulators in untreated MT-2 or treated with AZT (18 weeks). Equal amounts (50 μg) of each extract were used and confirmed by β-tubulin. (B) Absence of cleavage for procaspase 3 or PARP in AZT-treated MT-2 cells. (C) Senescence β-gal (SA-β gal) assay in MT-2 cells untreated and treated with AZT (18 weeks). A significant amount of senescence was detected only in end of cultures. (D) Western blot analysis of MT-2 cells treated with AZT. Samples were collected at different times after treatment from 0 to 15 weeks. Expression of caspase 3, Bcl-2, and Bax was tested. Actin was used as loading control. (E) Western blot analysis of MT-2 cells treated with AZT. Samples were collected at different times after treatment from 0 to 15 weeks. Expression of Tax was analyzed as described in “Patients, materials, and methods.” Beta-tubulin was used to confirm equal loading.