E2F1 and cancer: Critical signaling pathways that are regulated positively (PI3K/Akt, endoglin, sonic hedgehog [SHH], RAS-ERK, miR-21), negatively (ubiquitin-like with PHD and ring finger domains 1 [UHRF1]), or either positively or negatively (Wnt/b-catenin) by TH coordinate to modulate the expression of downstream targets implicated in cancer cell proliferation, such as E2F Transcription Factor 1 (E2F1), p21, c-myc, mTOR, and c-fos.