The env sequences from two feline mammary tumours (indicated by their respective ID archival number) were aligned with NIH 3T3 (positive control for MMTV), mouse mammary tumour virus from HeJ mice (Accession Number AF228551.1), HMTV (Accession Number AF243039) and two feline sequences previously deposited from [8]. Here, ERVW-1 is linked to breast cancer.