Curves of cell proliferation and COX-2 modulation after addition of rofecoxib at various concentrations in the MM cell lines. A, the graphs represent cell growth curves of the five cell lines treated with 4, 12, and 36 μM of drug (Rofecoxib) compared to cells treated with DMSO at the same final concentration of that present in medium with drugs (CNTRL) as described in material and methods. The survival of cells was expressed as absorbance (A 492 nm-A690 nm) and % of proliferation (on the right bottom). To evaluate the modulation of rofecoxib on COX-2, Ist-Mes-1, Ist-Mes-2 and MPP89 cell lines were treated with 36 μM rofecoxib for 48 h. The effect of the drug was evaluated by Western blot (B) and quantitative PCR (C). The table (D) displays IC50 in the cell lines more sensitive to rofecoxib.