“…Since there are several processes involved in causing PDT induced cell killing it is not surprising that any of the three commonly known cell death mechanisms, namely apoptosis, necrosis or autophagy can be triggered [5,10,23,26,54]. Confocal microscopy and Förster Resonance Energy Transfer (FRET) imaging on cultured cells demonstrated that common PDT PSs are found to localize in different subcellular structures such as the plasma membrane (Photofrin®), mitochondria (phthalocyanine Pc4), lysosomes, nucleus, endoplasmic reticulum or the Golgi apparatus [5,23,26,43,55].…”