SRC and breast cancer: Although PDS can bind to many G4s without selectivity, it is thought to constitute a suitable model for such a proof‐of‐concept study,[30] as exemplified by the use of PDS to reduce SRC proto‐oncogene expression in human breast cancer cells and to validated SRC‐G4 as a druggable target.[31] We first measured the half‐maximal inhibitory concentration (IC50) values of PDS to Hela, A431, and A549 cells to be 109.2, 204.4, and 203.5 μm, respectively (Figure S28A, Supporting Information).