TP53 and cancer: Frataxin, a mitochondrial iron chaperone, is required for the enzyme activity of FECH .36 Knockdown of p53 by siRNA reduced the levels of frataxin protein and increased 5-ALA-induced PpIX more than two-fold in human embryonic kidney cells (HEK-293T).37 Given that mutational p53 dysfunction is common during cancer progression, a consequent reduction in the expression of frataxin could reduce the level of functional FECH and thereby contribute to PpIX accumulation in tumour cells.