TP53 and B-cell chronic lymphocytic leukemia: To determine the mechanism of induction of apoptosis by PpIX in CLL cells, EHEB cells were treated with 2.5 μg/ml PpIX for 8 h and analysed for the expression of p53 and TAp73 apoptotic target genes BAX and PUMA by quantitative PCR (qPCR).