Functional analysis of cancer stem cell activity in DMBA-induced mammary tumors.

The frequency of tumor initiating cells (TICs) was compared for the total cell population (designated Lin−), and two cellular sub-fractions (luminal and basal cell populations), using fat pad assay of limiting dilutions of cell suspensions. Three series of cell populations were used: Primary tumor-D19 (Fig. 2), a second generation tumor-D192 (obtained from basal cell transplantation of primary tumor D19), and another second generation tumor-D12 derived from transplantation of a different primary tumor, D1 (Fig. 2).