CCR2 and Patent ductus arteriosus: Therefore, to examine the expression of the CCR2 ligand CCL2 in PDA, we first performed correlation analysis with human patient data and observed a significant correlation between CCL2 and CD14 (Figure 3A), as well as other macrophage markers such as CXCR4, CD206, CD163, and MHCII transcripts (not shown), further linking expression of CCL2 in tumors with myeloid cell infiltration.