The invention is composed of monoclonal human MN antibodies or MN antibody fragments that target the GEEDLP (SEQ ID NO: 118) repeat within the proteoglycan domain. The proteoglycan domain of the MN cell surface protein contains four of these identical GEEDLP (SEQ ID NO: 118) repeats. Binding to the desired epitope is verified by competition ELISA, where ELISA signal can be attenuated by co-incubation with a peptide containing this repeat (PGEEDLPGEEDLP (SEQ ID NO: 119)). This inhibition of binding can also be verified using Biacore assays, where binding of desired antibodies to immobilized MN or proteoglycan peptides can be inhibited by the peptide repeat. In addition to binding to the peptide repeat, human anti-MN antibodies can inhibit the cell adhesion of CGL-1 cells to MN coated plastic plates. Human anti-MN antibodies have been used to diagnose and quantify MN expression in cancer cells and tumors using FACS and immunohistochemical methods. An example is also provided where a human anti-MN IgG1 mediates tumor cell lysis though antibody-dependent cell-mediated cytotoxicity. Therefore, these antibodies will be useful for the treatment of cancers in which MN is upregulated or can be useful for the diagnosis of cancers in which MN is upregulated.