ID2 and cancer: ONC201 attenuates diverse CSC markers such as CD44, CD133, ABCB5, ALDH1A1, ALDH7A1, NANOG, ID1, ID2, ID3 [2, 3] and self-renewal signaling pathways such as Wnt, Notch and Hedgehog [15, 16, 19] that drive tumor-initiation [13, 21], therapy resistance [17] and metastasis [14, 18] across various tumor types providing an opportunity for broad-spectrum anti-CSC and anti-cancer effects.