Colony stimulating factor-1 (CSF-1) is a homodimeric glycoprotein that humorally regulates the proliferation and differentiation of mononuclear phagocytic cells and locally regulates cells of the female reproductive tract. Alternative splicing of the human CSF-1 mRNA leads to alternative expression of the CSF-1 homodimer as a secreted glycoprotein or as a membrane-spanning molecule with cell surface biological activity. CSF-1 is predominantly secreted as highly sulfated species of 375- and 250-kDa with a smaller amount of a 100-kDa species. The three predominant CSF-1 species were shown to be an 80-kDa homodimer, an 80-kDa/50-kDa heterodimer, and a 50-kDa homodimer. (PMID: 1733926) This antibody could recognieze 60 kDa, 48 kDa, 29 kDa isoforms.