Different levels of S. galili p53 have selective regulation to target genes under stresses. For different p53 levels, 0.2, 0.5, or 1 μg of S. galili p53 expression plasmid was transfected to BRL-3A cells under normal, acidic (pH 6.6), or hypoxia (1% O2) stresses. Expression of p53 and its target genes were determined using qPCR. Results are mean ± SEM (n = 3). *P < 0.05, **P < 0.01, and ***P < 0.001 compared with control groups with 0.2 μg p53 plasmid (unpaired t test). #P < 0.05, ##P < 0.01, and ###P < 0.001 compared with 0.2 μg p53 plasmid under acidic stress. &P < 0.05, &&P < 0.01, and &&&P < 0.001 compared with 0.2 μg p53 plasmid under hypoxia stress. +P < 0.05 compared between 0.5 μg and 1 μg p53 plasmid under normal condition.