CXCR4 and systemic lupus erythematosus: However, the expression levels of CXCR4 and CD44 show an overall decrease in each cell cluster of SLE conditions compared to HC conditions, and the decrease in CXCR4 and CD44 in each cell group led to the decrease in MIF–(CXCR4 + CD74) and MIF–(CD74 + CD44) ligand/receptor pairs.