IC50 values: luminometric assays. (A) Growth inhibition IC50 mean values in 8 DLBCL cell lines at 3 time points were explored for niacinamide. (B) Niacinamide induces weak growth inhibition in a spectrum of DLBCL. In 4 DLBCL lines, niacinamide induced concentration, but not time-dependent, growth inhibition. Values represent means expressed as percentages compared with the untreated control; error bars represent standard deviation.