Viability of HepG2 cells at one, three and five days after commencement of treatment. The groups include blank and free drug (FD) groups (blank, chi-p53 FD, Dox FD, and combined Dox and chi-p53 FD) as well as blank and drug loaded microsphere (MS) groups (blank MS, chi-p53 MS, Dox MS, and combined Dox and chi-p53 MS). The free drug groups represent equivalent amount(s) of Dox (0.9 μg/ml) and/or chi-p53 (1 μg DNA) released from the drug loaded microsphere groups after five days determined from in vitro release profiles. Data represent mean ± standard deviation, n = 4. Statistical significance (*p < 0.05) was determined by one-way ANOVA analysis as compared to the control group, while (**p < 0.05) was determined by Student’s t-test comparison between the two samples.