As the rate of tumor initiation was further influenced by the addition of KrasG12D mutation into p53fl/fl;myr-p110α, which has been shown to signal primarily through the PI3K/AKT pathway,30 we assessed the levels of PI3K signaling activation in p53fl/fl;myr-p110α mammary tumors with or without KrasG12D mutation. Here, PIK3CA is linked to breast cancer.