TABLE 2

CYP2A6 and CYP2A13 mRNA levels in human lung tissues with differing levels of CYP2A proteins

CYP2A6 and CYP2A13 mRNA levels were determined, using real-time RNA-PCR. Lung tissues that were found to have either relatively high (∼30–110 fmol/mg microsomal protein; CYP2A6-High) or low (<2 to ∼8 fmol/mg microsomal protein; CYP2A6-Low) levels of CYP2A6 were analyzed for CYP2A6 mRNA expression, whereas lung tissues that were found to have either relatively high (∼3–20 fmol/mg microsomal protein; CYP2A13-High) or low (<2 fmol/mg microsomal protein; CYP2A13-Low) levels of CYP2A13 were analyzed for CYP2A13 mRNA expression. RNA samples that failed to produce a positive signal after 50 cycles of real-time PCR were assigned an abundance value of zero copies for calculation of means and medians.