LiCl increases β-catenin activity in 5TGM1 myeloma cells in vitro. LiCl (10 mM) had no significant effect on 5TGM1 myeloma cell proliferation (A), but significantly increased axin2 mRNA expression (B) and expression of β-catenin (C). 5TGM1 myeloma cells were stably transfected with myc-tagged ΔNTCF4 or pcDNA (D). Wnt3A or LiCl treatment had no effect on proliferation of 5TGM1-pcDNA or 5TGM1-ΔNTCF4 cells (E). Overexpression of ΔNTCF4 completely blocked the increase in β-catenin activity as measured by TOPFLASH reporter activity (F). Data are expressed as means (± SEM). *P < .05 compared with control. **P < .01 compared with 5TGM1-pcDNA.