At higher concentrations, pretreatment with GPR15LG reduced CXCL12-induced Ca++ signaling in the BCR-ABL ALL cell line (Fig. 4d), and attenuated CXCL12-mediated CXCR4 C-terminal modification in primary CD4+ T cells (Fig. 4e). Here, GPR15LG is linked to acute lymphoblastic leukemia.