Transfection efficiency and apoptotic activity of wt-p53 loaded gelatin nanoparticles. (a) p53 mRNA expression in tumors. Results are presented as mean ± SD (n = 3 for day 7 and 18; n = 6 for day 33). mRNA expression level for downstream apoptotic markers after (b) day 7, (c) day 18 and (d) day 33. (n = 3 for day 7 and 18; n = 6 for day 33) (*p < 0.05; **p < 0.01; ***p < 0.001). (e) Western blot analysis for p53, cleaved PARP, cleaved caspase 3 and β-actin protein expression in treated tumors. (f) TUNEL analysis of apoptotic activity in the wt-p53 treated tumors. Sections of tumor tissues imaged after treatment for 7, 18 and 33 days for TUNEL positive (brown) cells. All images were acquired at 20× with scale bar of 50 μm.