HMOX1 and preeclampsia: To determine whether HO-1 haploid deficient mice (Hmox1+/−) in the presence of high sFlt-1 cause preeclampsia-like symptoms, Hmox1+/+ and Hmox1+/− pregnant mice were injected with either Ad-CMV or Ad-sFlt-1 via tail vein injection on day E11.5.