PIK3CA and breast cancer: First, in the light of these literature evidences, second, with closer association of activated RAS, EGFR, MYC and E2F signaling with EXO1 expression, and third with the series of in vitro experiments (Figure 3 & 4), for the first time we report the regulation of EXO1 in breast cancer cells through EGFR/RAS/PI3K/AKT/MYC/E2F signaling cascades (Figure 7).