Here, we tested the TERT promoter MPRA library in two different cell types, HEK293T and glioblastoma SF7996 cells52, referred to here as GBM (Fig. 2a), observing a log2 fold increase in promoter activity of 2.00/2.86-fold for c.-124C>T and 1.42/2.42-fold for c.-146C>T in HEK293T and GBM cells, respectively. Here, TERT is linked to glioblastoma.