CDKN2C and breast cancer: Due to the haploinsufficient role of p18 in mammary tumor development 7, 55 and the indistinguishable mammary tumor phenotype between p18-/- and p18+/-, as well as p18-/-;Gata3+/- and p18+/-;Gata3+/- mice, we combined p18-/- and p18+/- mice as p18mt group, p18-/-;Gata3+/- and p18+/-;Gata3+/- mice as p18mt;Gata3+/- group.