TF and cancer: By extracting all pan-cancer FFLs that involve cyclin family members (Supplementary Figure S2C), we found dense regulations between miR-15 family and cyclin family, and all of them were targets of E2F1 (Supplementary Figure S2D), indicating that E2F1 was a pan-cancer TF, and achieved its function through FFLs with the miR-15 family and the cyclin family.