Figure 2.

PTK6 transgenic animals display increased susceptibility to mammary gland tumor development. Nontransgenic FVB/N control and three independently developed MMTV-PTK6 transgenic mouse lines were maintained for 2.5 years and mammary gland tumorigenesis was monitored. Transgenic mice developed multiple mammary gland tumors during this period, and nontransgenic animals also developed spontaneous mammary gland tumors. The mammary gland tumor occurrence was shown as the percentage of animals that developed breast tumors relative to the total animal number. The Cochran-Armitage Trend test validated the hypothesis that increased numbers of MMTV-PTK6 transgenic animals develop mammary gland tumors than nontransgenic mice (P=0.042).