PIK3CA and neoplasm: These studies demonstrated nonlinear clonal expansion of the original tumors and allowed the identification of some oncogenic pathways involved in tumor progression, including activation of MYC and RTK-RAS-PI3K pathways, upregulation of the cell cycle transition factors FOXM1 and E2F2, epigenetic silencing of transcription factors bound by Polycomb repressive complex 2 [102].