(A) Increased phosphorylation of Raf-1 (p-Raf-1), ERK1/2 MAPK (p-ERK1/2) and Raf-1 kinase inhibitor protein (RKIP) (p-RKIP) in normoxic CCL39 cells stimulated by 5-HT (1 µM; 5 min) was potentiated by the RKIP inhibitor locostatin (5 µM; added 45 min prior to the addition of 5-HT). (B) Quantification of data is also shown representing three independent experiments with comparable outcomes [samples were adjusted for loading errors, using the tubulin blot density to standardize, prior to normalization relative to control (unstimulated) values]. Quantitative data are shown as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, significantly greater than control (unstimulated) value. †P < 0.05, ††P < 0.01, significantly greater than corresponding value in the absence of RKIP inhibition.