CCL2 and Mycobacterium infection: To confirm the active role of the Cxcl12/Ccl2/Ccr2 signalling axis as a downstream effector mechanism of miR-126 expression and its involvement in the increased migration of macrophages to sites of mycobacterial infection, the cxcl12a and ccr2 genes were targeted for knockdown using CRISPR-Cas9.