A. Left: Telomerase activity measured using ddTRAP assay. The horizontal pink lines represent the threshold used in these samples for background correction. Each dot on the ddPCR output represents a unique droplet that is either positive or negative for fluorescent signal. Right: Quantification of TRAP activity after normalization to SW39/TEL+ cells (n=3). Data information: Data are presented as mean ± SD. Statistical analyses were performed with Student's two-tailed unpaired t-test with Welch's correction for normality of distribution unless specified otherwise. PTM, post-translational modification. 