Assay of G-rich 3′ overhang length in CLL cells according to their in vitro sensitivity to apoptosis. G-rich 3′ overhang lengths are expressed as nucleotides (nt). (A) Representative example of a 3′ overhang length measurement using the T-OLA analysis. As indicated, 2 probes were tested: one complementary to the 3′ overhang (CCCTAA)₈ and one homologous to the 3′ overhang sequence (negative control; TTAGGG)₈. (B) Comparison of the 3′ overhang lengths between CLL-R and CLL-S. Values are the mean 3′ overhang length (nt) ± SD (n = 10 for both CLL-R and CLL-S). The Mann-Whitney U test was used to assess statistical significance: ***P < .001.