Lithium inhibited GSK-3β in RG3.6 cells, and other GSK3β inhibitors mimicked lithium's effect on RG3.6 cell growth. (A) RG3.6 cells were grown in culture medium containing 3 mM LiCl or 3 mM control NaCl for 3 days, followed by western blotting analysis on P-GSK-3β (Ser9) and GSK-3β expression. (B) The blotting results in A were analyzed using ImageJ software (http://rsb.info.nih.gov/ij/, 1997-2007), and the ratio of P-GSK-3β was plotted. (C) Other GSK-3β inhibitors, like lithium, also increased cell numbers in RG3.6 cell cultures. Cell count analysis was performed on RG3.6 cells grown for 6 days in culture medium without or with 3 mM LiCl, 0.1% DMSO, 5 μM SB216763, or 25 μM SB415286 (n = 6 for each condition). DMSO was used as the vehicle control for SB216763 and SB415286, since these two drugs were dissolved in DMSO. The data represent mean ± standard error, and significance was determined with Bonferroni/Dunn post hoc analysis following ANOVA.