Fig. 7. ßGA alters the viability of both neural progenitors and differentiating cells. Viable cells of either floating (A) or adherent (B) neurospheres were quantified colorimetrically by the MTT assay (see Materials and Methods) following three days in the presence of the specified drugs. Data were normalized to the values measured under control conditions. The gap junction inhibitor ßGA caused a significant reduction of cell viability at all concentrations tested, whereas neither the inactive analog GZA nor solvent (DMSO/ethanol, DE) affected the total number of viable cells. Results are shown as means±s.e.m. of three independent experiments. Statistical significance was analyzed using the unpaired Student's t-test (^*P<0.01).