Podocalyxin, a sialoglycoprotein, is thought to be the major constituent of the glycocalyx of podocytes. It is a member of the CD34 family of transmembrane sialomucins. It is involved in the regulation of both adhesion and cell morphology and cancer progression. It functions as an anti-adhesive molecule that maintains an open filtration pathway between neighboring foot processes in the podocyte by charge repulsion. Podocalyxin acts as a pro-adhesive molecule, enhancing the adherence of cells to immobilized ligands, increasing the rate of migration and cell-cell contacts in an integrin-dependent manner. Sialylated, O-glycosylated glycoforms of podocalyxin expressed by colon carcinoma cells possess L-selectin and E-selectin binding activity, and may be pivotal to the metastatic spread of colon carcinoma cells.