ICL3-FLNA interaction regulates CXCR4-induced ERK1/2 activation. (A-B) X4^WT- and X4^WHIM-expressing (A) A7 and (B) M2 cells were stimulated with CXCL12 for the times indicated. Phosphorylated (top) and total (bottom) ERK1/2 levels were determined by immunoblot with specific antibodies (n = 3). (C) Phosphorylated (top) and total (bottom) ERK1/2 levels after CXCL12 stimulation were determined as above in HEK-293 cells transfected with X4^WHIM and X4^WHIM-ICL3ΔCt. A representative experiment is shown (n = 3). (D) Kinetics of CXCL12-induced ERK1/2 activation in HEK-293 cells as in (B), determined by densitometric analysis. Values were normalized by using the phosphoERK:ERK ratio in unstimulated cells for each receptor. Data shown as mean ± SEM; *P < .05, 2-way ANOVA with Bonferroni posttest. (E) HEK-293 chemotaxis was assayed in transwell devices by using the indicated doses of CXCL12 as a chemoattractant. Data are mean ± SEM in a representative experiment. Curves with distinct letters differ significantly from one another (n = 3; Student-Newman-Keuls test, P < .05).