Acriflavine, a mixture of 3,6-diamino-10-methylacridnium chloride (trypaflavine) and 3,6-diaminoacridine (proflavine), binds to the PAS-B domain of HIF-1α [91,92] and thereby prevents HIF-1 dimerization and inhibits transcription of HIF-1’s target genes, leading to antitumor effects without obvious adverse side effects in PC-3 xenograft tumor models. The gene discussed is HIF1A; the disease is neoplasm.