CXCL12 and neoplasm: The few receptor/ligand pairs that were consistently different between plaque/tumor vs. patch lesions included SELL - CD34 (malignant cells/lymphatic endothelial cells), CXCL12 - CXCR4 (fibroblasts/malignant cells), and CCL5 - CCR4 (cytotoxic T cells/malignant cells), all of which were downregulated with skin lesion progression (Fig. 4 E, Table S5).