Reducing expression or inhibiting CK2α activity decreased GBM tumorigenesis in vitro. A, siRNAs specific to CK2α (siCK2α) and CK2β (siCK2β) were introduced into U87-MG and U138 cells. A scrambled nonspecific siRNA (siScr) was used as a control. The numbers under each blot correspond to the fold change in protein levels relative to the control. B, cell growth analysis of U87-MG transfected with siRNA. The cell lines were cultured in 10% fetal bovine serum and viable cells were counted daily. Results are from two separate experiments, each done in triplicate. C, anchorage-independent growth of U87-MG cells treated with siRNAs. D and E, cell growth analysis of U87-MG treated with CK2 inhibitors TBBz or CX-4945. F, anchorage-independent growth of U87-MG cells treated CK2 inhibitors in soft agar. Results are from two separate experiments, each done in triplicate. *represents a statistically significant change from the control, P < 0.05, as measured by the Mann–Whitney U test