The effect of GSK-3β inhibition was observed in the U2OS cells after knock-down of β-catenin expression (Supplementary Figure S5B), suggesting that β-catenin signaling-independent mechanism(s) such as alteration in NF-κB activity [25] may underlie the efficacy of GSK-3β inhibition against U2OS osteosarcoma cells. Here, NFKB1 is linked to osteosarcoma.