Expression of HML-2 proviruses is known to be up-regulated in tissues associated with several diseases, including breast cancers [21-25], germ cell tumors [26-29], melanomas [30-33], ovarian cancer [34,35], leukemias/lymphomas [36,37], schizophrenia [38-41], and rheumatoid arthritis [42-45], as well as during HIV infection [46,47], in which transcripts, proteins, and even retrovirus-like particles originating from HML-2 proviruses have been observed. This evidence concerns the gene CLEC10A and breast cancer.