The ChIP assay was performed according to the protocol for the fast ChIP method53. Briefly, cells were cross-linked with 1% formaldehyde for 10 min, followed by incubation with 125 mm glycine for 5 min at room temperature. Cells were then lysed and sonicated 7 times for 15 s with 45 s rest between pulses at 40% pulse power using a Branson 150D Sonifier Liquid Processor (Branson Ultrasonic Corporation, Danbury, CT). The cross-linked protein/DNA was incubated with anti-FOS, anti-MYC, anti-GABPA, or anti-GABPB antibodies, or non-specific IgG overnight at 4 °C and purified by Protein A/G PLUS-Agarose (sc-2003, Santa Cruz Biotechnology). The precipitated DNA fragments were isolated with Chelex 100 resin (Bio-Rad Laboratories, Hercules, CA) and subjected to PCR amplification of the GABPB promoter region and the mutation-containing region of the TERT promoter using the primers listed in Supplementary Table 2. The uncropped gel images corresponding to the main figure are provided in Supplementary Fig. 6.