Pyridostatin is a synthetic small-molecule stabilizer of G-quadruplexes, a secondary structure of DNA that usually exists in the end of the chromosome or the telomeres. It can compete for binding with the telomere-associated proteins and induce telomerase dysfunction. Pyridostatin induces DNA damage and cell cycle arrest (Kd = 490 nM) and has been shown to target the proto-oncogene Src, reducing Src protein abundance and Src-dependent motility in human breast cancer cells.