VCAM1 and atherosclerosis: The basis by which macrophage-to-endothelial cell crosstalk by 27HC participates in atherosclerosis development was further delineated with the finding that increases in endothelial cell ICAM-1 and VCAM-1 expression above those found in the absence of macrophage cyp27a1 and endothelial ERα were only promoted by macrophage cyp27a1 in mice expressing the receptor in endothelium (Fig. 2n, o).