Interpretation of RTPCR data revealed that exposure of Hep-G2 cancer cells to IC50 (6.21 μg/ml) of Er2O3-NPs for 72 h resulted in statistically significant (p < 0.05) elevations in the expression levels of the p53 and Bax (apoptotic) genes and decreases in the expression level of Bcl2 (anti-apoptotic) gene compared to their expression levels in the untreated Hep-G2 cells (Fig. 8). This evidence concerns the gene TP53 and cancer.