Figure 3.

Expression of normalized β₂AR mRNA in murine tracheal epithelial cells exposed to the indicated concentrations of PAHs in DMSO or DMSO-only vehicle in complete medium for 24 hours. Messenger RNA was quantified according to real-time RT-PCR, as described in Materials and Methods. The data are normalized to same-cell glyceraldehyde 3-phosphate dehydrogenase (GAPDH) mRNA. Signal intensity was arbitrarily set at 100 for control cells treated with 8.4% DMSO, to permit comparisons among groups. *P < 0.01 versus all other groups (n = 6 samples/condition).