Identification of small molecules which inhibit GSK-3 in vivo. HeLa and DLD-1 cells were incubated with small molecule GSK-3 inhibitors for 24 hours then analysed by immunoblotting and immunofluorescence. (A) Immunoblot of HeLa cell extracts showing inhibition of glycogen synthase phosphorylation by a subset of GSK-3 inhibitors. (B) Immunoblot of HeLa cell extracts showing that GSK-3 inhibitors do not inhibit Cdk1 phosphorylation of nucleolin. (C) Images of mitotic DLD-1 cells showing examples of abnormal metaphase spindles following exposure to AR-A014418 and 1-Azakenpaullone. (D) Bar graph plotting the number of abnormal metaphases in cells treated with different small molecule GSK-3 inhibitors.