Dependence of GFP-TAT transduction on PC12 cell GAG content. (A) The average µg of GAG / ng of DNA, normalized to the average µg of GAG / ng of DNA in undifferentiated cultures is shown for undifferentiated PC12 cells treated to experimentally alter GAG content (n>4, error bars: ±SEM). There was a significant increase in GAG with differentiation, and a significant decrease in GAG with trypsin treatment. (B) Geometric mean fluorescence of GFP-TAT was normalized to undifferentiated PC12s (n>4, error bars: ±SEM). GFP-TAT transduction significantly increased in NGF-treated PC12 cells, and significantly decreased in both trypsin and heparin treated cells. *Significance from Dunnett post-hoc comparison to the control, undifferentiated condition. (C) Percent increase in GFP-TAT transduction, compared to GFP alone, showed a positive correlation with GAG content (n>4, three data points correspond to trypsin-treated, untreated, and NGF-treated PC12 cells, error bars: ±SEM), indicating that GAG content influences the ability of TAT to enhance GFP transduction.