Effect of serum reduction on CHO cell growth in NPD medium. Panel A: CHO cell growth in complete medium: Cells were seeded at an initial density of 1.5 × 106 per 10-cm Petri dish in NPD and DI based medium in triplicates. After overnight growth they were detached by trypsinization and counted. The results are given as the number of viable cells. Each column represents a mean number of cells in each treatment. The error bars denote the standard error of the means. The difference between the treatments is 30%. The graph provides a representative result of an experiment, which was conducted with replicates and repeated three times. Panel B & C: CHO cell growth in reduced-serum medium: Cells were seeded in 96-well plates in multiple replicates (18 wells per treatment) in NPD or DI medium supplemented with 5% (Panel B) or 1% (Panel C) FCS. The results were quantified and analyzed by means of crystal violet dye retention assay. Each column represents the mean cell density following a given treatment in O.D. units. The error bars denote the standard error of the mean. *Significant difference between NPD and DI grown cells p = 0.0006, total difference 7%. **Significant difference between NPD and DI grown cells p = 0.0001, total difference 14%.