We developed a lentiviral anti-miR screen as a way to identify miRs that play a regulatory role of telomerase in HeLa cells. In brief, we transduced HeLa cells with an anti-miR library encoding conserved and well-characterized miRs that neutralize the corresponding endogenously expressed miR in the transduced HeLa cells. The lentivirus also encodes copGFP (green) and puromycin for positive selection of transduced cells. This approach favors a physiologically relevant response by avoiding potential artifacts resulting from ectopic overexpression in cells, which does not normally express a specific miR. Following transduction of the anti-miR library or control miRs, we performed single cell dilutions into 96-well plates and performed a qPCR based functional assay of telomerase activity, using the telomeric repeat amplification protocol (q-TRAP) . The q-TRAP assay involves extension of an oligonucleotide through telomerase-mediated enzymatic addition of telomeric DNA repeats and subsequent PCR amplification of the extension products and serves as a great high throughput functional assay for telomerase activity in cells (Figure 1A). Shown in Figure 1B is a panel of miR controls (Controls) and one positive control, tested in parallel with samples, which had been transduced with the anti-miR library (Samples) and plated in single cell dilution and analyzed for telomerase activity.