Fig. 4. Synergism between CXCR4 and IL7R in BCR-ABL1-induced cell.

a BCR-ABL1 acts downstream of CXCR4. Shown are flow cytometry plots for Ca²⁺ mobilization in response to CXCL12 treatment (100 ng/ml) in WT as compared with BCR-ABL1-transformed cells with or without kinase inhibitor treatment as indicated. The results are representative of three independent experiments. b Proximity ligation analysis (PLA) to detect the close association of IL7R and CXCR4 on the surface of WT BM-derived pre-B cells as compared with mature B cells (which lacks IL7R expression; Supplementary Fig. 8a). c PLAs showing increased association of IL7R and CXCR4 on the surface of BCR-ABL1-transformed cells. d PLA showing recruitment of JAK3 to CXCR4 in BCR-ABL1-transformed cells. This association was lost upon inducible deletion of Il7r using Cre-ER^T2 (IL7R^∆) system. Close proximity is represented by red dots. b–d Quantification shows number of signals per cell, error bars represent mean ± SD. Unpaired t-test, two-sided. The results shown are representative of three independent experiments. Exact p values (c) 0.00000000006167, approximate p value (b) <0,000000000000001, approximate p value (d) <0,000000000000001. e Left panel, western blot analysis for increased phosphorylation of the JAK kinases by BCR-ABL1 activity. Right panel, western blot showing that inducible deletion of CXCR4 or IL7R results in reduced phosphorylation of all JAK kinases. The results are representative of three independent experiments. KDa kilo Dalton.