Calculation of the number of breast cancer cells with stem cell (tumor initiating) capacity by the Extreme Limiting Dilution Analysis (ELDA) method using R showed that on average 1 out of 10 MCF7 cells have the potential to initiate a tumor >100mm3 while overexpression of FOXO3A(A3) resulted in a ∼300 fold decrease in breast cancer initiating cell frequency (1 into 2778 MCF7 cells) (Table 1B). Here, FOXO3 is linked to breast cancer.