CK1δ/ε inhibitor PF-670462 specifically blocks interaction of primary CLL cells with microenvironmental stimuli in vitro. (A) Scheme of the applied treatments and analyzed CLL-microenvironment interactions. (B-E) Migration of primary CLL cells (N = 10-27) in presence or absence of PF-670462 was assayed using transwell assays. Cells were stimulated by 200 ng/mL CXCL12 (B) or CCL19 (C), BM stromal cells M210B4 (D), or ECM component fibronectin (E) stimulation. CK1 inhibitor treatment significantly blocked response to chemokines (P < .0001 both for CXCL12 and CCL19, N = 27), BM stroma (P < .0001, N = 15), and ECM (P = .0020, N = 10). MI, migration index.