Updated project metadata. Hyperoxia is known to cause cerebral white matter injury in preterm infants. Preterm birth is also associated with sudden hormonal changes which includes drop of estrogen level and increased postnatal production of fetal zone steroids (FZS). Therefore, we investigated the effect of hyperoxia (80% O2) and the subsequent administration of FZS on the proteins of immature oligodendrocytes using the OLN93 (rat-derived OPC) cell line as an experimental model. We demonstrate that hyperoxia has a negative effect on migration and associated signalling pathways, and that FZS and estrogen have distinct effects on these alterations.