Figure 3.

Fig. 3A. Immunoblot analyses confirm the presence of all tobacco-associated nitrosamine metabolizing P450 enzyme proteins in normal human oral mucosa. As a positive control, human liver homogenates were included. Fig. 3B. The histogram and accompanying Table (relative protein levels i.e. band density ratios of individual enzyme versus β-actin) depict relative P450 enzyme levels as normalized to the loading control β-actin and quantified by densitometry analysis. There is an approximate 2 fold inter-donor difference in enzyme levels for every P450 analyzed. Also, relative to human liver, oral mucosal P450 levels are appreciably lower.