A functional FGFR3 is ectopically expressed in t(4;14) myeloma cells.

(A) Delta-47, with no t(4;14) translocation, and OPM2 cells, with a t(4;14) translocation, have been stained by indirect immunofluorescence using rabbit polyclonal anti-FGFR3 primary antibody and goat antirabbit IgG FITC-conjugated secondary antibody (green signal), both at 1:200 dilution. Cell nuclei have been counterstained with DAPI (blue signal). (B) Flow cytometric analysis of nonpermeabilized OPM2 cells was performed on staining with anti-FGFR3 antibodies (gray line) or rabbit preimmune serum control (black curve), followed by secondary FITC-conjugated goat antirabbit IgG. Results shown represent fluorescent cells after gating on live cells. (C) aFGF induces ERK1 and ERK2 phosphorylation in MM cells expressing FGFR3. MM cells with no (KMS12) or with (LP1, KMS11, H929) t(4;14) translocation were starved for 48 hours and then stimulated for 10 minutes with 10 ng/mL aFGF in the presence of 10 μg/mL heparin. Cell lysates were analyzed by Western blot using anti–phospho-p42/p44 MAPK antibody. As loading control, the same blot was stripped and reprobed with anti-p42 MAPK antibody. The intensity of each phospho-MAPK band was measured and normalized against the p42 loading control, and the fold induction of phospho-MAPK was calculated as shown in the graph.