Figure 4. Comparisons of downregulated NEP mRNA expression by DEP and its components in cultured BEAS-2B cells.

Cells were treated with (1) DEP (SRM 2975); (2) DEP without transition metals, using chelators (cDEP); (3) carbonaceous core, represented by stripped DEP (sDEP); and (4) another type of particle, oDEP, or standard urban dust (SRM 1649a), at 0, 1, and 10 µg/cm² for 24 hours. The mRNA levels were determined by RT-PCR and normalized to endogenous references (GAPDH and 18S rRNA). Values represent the means ± SEM (% of controls) of 3 independent experiments (*P < 0.05).