Quantitative PCR analysis of RA pathway components at postnatal day 5 (P5) comparing mice with tobacco toxin exposure during lung development (TT, N = 9) to tobacco naïve (NS, N = 5) mice. All results normalized to expression of 18 S. Compared to NS mice, lung tissue samples from mice with TT had decreased expression of retinoic acid receptors (RAR) alpha and beta, retinoid X receptor (RXR) alpha, nuclear receptor family 2, group F, member 2 (Nr2f2) – also known as chicken ovalbumin upstream promoter transcription factor 2 (COUP TF 2), retinaldehyde dehydrogenase 1 (Raldh1), and cytochrome P450 26b1 (Cyp 26b1). Data are presented as mean ± SEM. NS = tobacco naïve. Data comparison performed using Student’s t-test for normally distributed data and Mann–Whitney for non-normally distributed data.