AZT-induced telomerase inhibition and telomere shortening in ATL patients. (A) Inhibition of telomerase activity measured by TRAP in vivo in ATL patients before and during treatment with AZT. (B) FACS analysis of telomere size by Flow-FISH in CD25⁺ and CD25– cells isolated from uncultured ATL patient samples. (C) Detection of exon 1 and 2 of the p14^ARF gene by PCR in CD25⁺ cells from 2 ATL patients before AZT treatment or after AZT treatment; GAPDH amplification was used as control. D indicates diagnosis; R, relapse/death; and CR, complete remission. (D) Detection of provirus integration site by inverse PCR before and after AZT treatment. Arrows indicate different integration sites by inverse PCR.