Rats.

Question to Carlos: Why rats??

Rats

Mice model using swiss mice (12 week old, females).

Because 4T1 cells are available to establish aniaml model for breast cancer, also 4T1 can be used for in vitro study or to replicate in vivo study to in vitro.

Advanatge of rat is to get sample size is large and disadvanatge is very difficult to handle rats. If you are beginer.

Characteristics of carcinogenesis in rats, like estrogen-sensitivity, are closer to those in humans. Those of mice are rather Prolactin-dependent which is not the case of most human breast cancer.

Dear Carlos

Thank you so much for a valuable point.