CXCL12 and chronic obstructive pulmonary disease: Treatment of HBEC-KRASV12high cells with neutralizing antibody against SDF-1 did not abrogate the modulation of CICs cells induced by COPD-EVs, indicating that SDF-1-CXCR4 activation axis was not central in COPD-EVs induced expansion of CICs (Fig. 4A).