VCAM1 is important in cell-cell recognition. Appears to function in leukocyte-endothelial cell adhesion. Interacts with the integrins alpha4 beta1 (beta 1 integrin VLA4) and alpha4 beta7 on leukocytes, and mediates both adhesion and signal transduction. The VCAM1/VLA4 interaction may play a pathophysiologic role both in immune responses and in leukocyte emigration to sites of inflammation. VCAM1 is also expressed by several non endothelial cell types including some macrophages, follicular dendritic cells and bone marrow, stromal cells.