Several amplified and overexpressed genes have been identified on this chromosome, such as BTAK in gastric, breast and ovarian cancer, MYBL2 and ZNF217 in breast and ovarian cancer, NABC1 in breast cancer, TGIF2 and PTPN1 in ovarian and breast cancer, and AIB1 in gastric, ovarian, pancreatic and breast cancer (Collins et al, 1998; Knuutila et al, 1998; Ghadimi et al, 1999; Forozan et al, 2000; Imoto et al, 2000; Sakakura et al, 2000, 2001; Tanner et al, 2000). This evidence concerns the gene PTPN1 and breast cancer.