PIK3CA and neoplasm: To elucidate the molecular mechanisms mediating tumor development in PIK3CA/Yap injected mice, we analyzed the key downstream signaling pathways of PI3K and Yap cascades in preneoplastic and neoplastic liver lesions from PIK3CA/Yap mice by immunohistochemistry (Figures 2, 3, 4; Supplementary Figure 2; Supplementary Table 2).