The effect of the PERK inhibitor on activation of caspases-9 (the initiator) and -3 (the effector) in C6/36 cells with dengue 2 virus (DENV2) infection by using FACScan flow cytometry. ( A ) In DENV2-infected C6/36 cells (MOI = 1), no evident change in caspase-9 had occurred in cells by 24 h post-infection (hpi), even when they were treated with a PERK inhibitor (5 μM). However, it had increased by 48 hpi (2.52-fold increase) compared to the two control groups (1.20- and 1.18-fold for untreated and DMSO-treated cells, respectively; Student's t -test; *** p