The TRA-1-60 monoclonal antibody reacts with a pluripotent-stemcell- specific antigen expressed on undifferentiated human embryonic stem (ES) cells, embryonal carcinoma (EC) cells, and embryonic germ (EG) cells. The expression of TRA-1-60 on human ES cells is downregulated upon differentiation. The TRA-1-60 antibody recognizes a neuraminidase-resistant carbohydrate epitope expressed on podocalyxin, a member of the CD34-related family of sialomucins. Podocalyxin is a transmembrane glycoprotein, which has been implicated in the development of aggressiveness in a variety of cancers, including breast and prostate cancer.