CASP9 and diffuse large B-cell lymphoma: Notably, as the cleavage of caspase-3, caspase-9, and PARP is significant process in cell apoptosis, high-concentration PGD2 was observed to increase the expression of Bax, and the proportion of cleaved forms of caspase-3, caspase-9 and PARP (Fig. 3F), indicating the activation of apoptosis process in DLBCL cells.