[5] MCAM functions as a receptor for laminin alpha 4,[6] a matrix molecule that is broadly expressed within the vascular wall.

Its function is still poorly understood, but evidence points to it being part of the endothelial junction associated with the actin cytoskeleton.

It is expressed on chicken embryonic spleen and thymus, activated human T cells, endothelial progenitors such as angioblasts and mesenchymal stem cells, and strongly expressed on blood vessel endothelium and smooth muscle.

CD146 has been demonstrated to appear on a small subset of T and B lymphocytes in the peripheral blood of healthy individuals.

Without the expression of MCAM melanoma cells are controlled by keratinocytes in the epidermis that inhibit penetrance beyond the basement membrane.