Nrf2-responsive genes and oxidative stress related genes were examined by quantitative real-time PCR on samples from cells expressing wild type (Q23) and mutant (Q74) huntingtin for 0, 1 and 5 days. All values are expressed as relative mRNA levels compared to expression levels on day 0 (uninduced cells) with β-actin and Ywhaz as reference genes. A: Nrf2 and Nrf2-responisve genes involved in detoxification. NRF2: NF-E2 related factor 2, NQO1: NAD(P)H dehydrogenase quinone 1, GSTA4: glutathione S-transferase alpha 4, GSTP2: glutathione S-transferase pi2. B: Nrf2-responsive genes involved in antioxidant/reducing potential. CAT: catalase, GCLC: the catalytic subunit of glutamate-cysteine ligase, GCLM: the modifier subunit of glutamate-cysteine ligase, HMOX1: heme oxygenase 1, TALDO1: transaldolase 1, FTL1: ferritin light chain, Me1: malic enzyme 1. C: Non-Nrf2 responsive genes involved in protection against oxidative stress. GPX1: glutathione peroxidase, SOD1: superoxide dismutase 1, SOD2: superoxide dismutase 2, MT3: metallothionein 3. * Represents significant differences between the day 1 and day 5 time points (* P < 0.05, **P < 0.005, ***P < 0.0005 student's t-test). + Represents significant differences.