(d) ER stress inducers trigger caspase-8 and caspase-3 activation in NRBF2 KO MEFs. MEFs were treated with DMSO, 1 μM TP or 1 μM TN for 24 h, and then immunoprobed with indicated antibodies. Marked accumulation of cleaved caspase-8 (C-Cas 8; p43 and p18 units) and cleaved caspase-3 (C-Cas 3) are observed in the NRBF2 KO MEFs but not WT MEFs treated with TP or TN. This is a representative image from three independent experiments. 