Lactadherin (also known as milk fat globule factor 8, MFG-F8) is a 47 kDa glycoprotein that was found in milk fat globule membranes. Lactadherin is secreted into milk by mammary epithelial cells of humans, cows and mice. Its presence in milk is associated with protecting a breast-fed children against rotavirus infections. The protein is also produced by vascular smooth muscle cells, endothelial cells and macrophages.