ATF3 induction by M344 is independent of MAPKinase pathways. A, A549, MCF-7, PC3 and SKOV-3 cells untreated (control), and treated with DMSO, or M344 (5 μM) for 24 hrs in the absence (control) or presence of MAPKinase pathway inhibitors SP600125 (50 μM), UO126 (25 μM), and SB203580 (10 μM) and analyzed by Western blotting for ATF3 and actin. B, MCF-7 cells untreated (control), treated with DMSO, TNFα for 15 min, or with M344 (5 μM) in the absence or presence of p38 inhibitor, SB203580 (5 and 10 μM) for 24 hrs were analyzed for ATF3, actin, phospho-HSP27 (p-hsp27), and total HSP27 expression by Western blotting. C. ATF3 mRNA quantified by quantitative RT-PCR of MCF-7 cells untreated (control), treated with M344 (5 μM) or M344 in the presence of SB203580 (10 μM) for 24 hrs. Error bars are representative of quantified mRNA from three independent experiments.