Lastly, it was demonstrated that inhibition of HIF-1α with acriflavine, a small molecule that prevents the dimerization of HIF-1α with HIF-1β and thus its activation [40], potentiated PDT efficacy in human epidermoid carcinoma (A431) cells and SK-ChA-1 cells using liposomal ZnPC Broekgaarden et al., Inhibition of hypoxia inducible factor 1 with acriflavine sensitizes tumor cells to photodynamic therapy with zinc phthalocyanine-encapsulating cationic liposomes, in preparation [41]. The gene discussed is ARNT; the disease is squamous cell carcinoma.