PIK3CA and breast cancer: Moreover, in breast cancer, activation of the PI3K/Akt pathway by Nectin-4 induces the activation of the Wnt pathway and then affects the proliferation of tumor stem cells, which is an important mechanism by which cancer stem cells achieve self-renewal.123 Communication between the Wnt/β-catenin and PI3K/Akt pathways has been observed in different types of human cancer, and PI3K/Akt pathway activation leads to Wnt/β-catenin pathway inhibition.