The G-rich element of the proximal promoter in the gene for PDGF-A also forms a stable G4 structure, even in the duplex context, and TMPyP4 reduced the basal promoter activity of PDGF-A, suggesting that targeting the PDGF-A G4 by the ligand specific for this G4 may be feasible as a cancer therapy for gliomas, sarcomas, and astrocytomas [204,207,208,209,210,211]. Here, PDGFA is linked to cancer.