As far as I know, Ma-Balb is a mouse breast cancer cell line tumorigenic in Balb/C mice. I think it could be an interesting breast cancer model because you don't have to buy nude mice (very expensive), but I cannot find information about ER/PR, HER2, EGFR, Ki-67 expression, number of cells to be inoculated in mice, etc. Does anybody have experience with this model?