HMOX1 and preeclampsia: Incubation with preeclampsia plasma induced a significant increase in SOD1 gene expression (1.32 ± 0.10 fold, n = 8, P < 0.05), SOD2 gene expression (1.35 ± 0.21 fold, n = 8, P < 0.05) and HO-1 gene expression (1.82 ± 0.42 fold, n = 8, P < 0.05) respectively compared to uncomplicated pregnancy (Fig. 4a).