Figure 2

Dox-induced ERK1/2 activation promotes survival of human MM cells. A. Three MM lines (MO, ME-26 and HMESO) were pretreated with U0126 or U0124 (20 μM, 1 h) before treating them with an LD₅₀ dose of Dox for 24 h. Cell viability was assessed using the MTS assay as described in 'Materials and Methods'. A combined treatment of U0126 and Dox caused significantly increased cell death as compared to either treatment alone (grey bars). *p ≤ 0.05 as compared to untreated control. †p ≤ 0.05 as compared to Dox alone group. N = 3-6 per group. B. HMESO or PPMMill cells were stably transfected with either shERK1 or shERK2 as described in the 'Materials and Methods'. These stable MM lines were treated with Dox (100 μM) for 24 h and cell viability was assessed using the MTS assay or cell counting. Inhibition of ERK1 or ERK2 significantly enhanced Dox-induced cell killing. *p ≤ 0.05 as compared to respective untreated control. †p < 0.05 as compared to Dox treated shControl (shCon). ‡p ≤ 0.05 as compared to shERK1 Dox group. N = 6 per group.