JNK activation-mediated apoptosis in cerebral vascular endothelial cells and oligodendrocyte progenitors in the white matter after lipopolysaccharide-sensitized hypoxic-ischemia. Immunofluorescence of the lipopolysaccharide (LPS) + hypoxic-ischemic (HI) group 24 h post-insult showed numerous phospho-c-Jun N-terminal kinase (p-JNK)-positive cells attached to or located around the microvessels in the white matter (A). RECA-positive endothelial cells (A) and O4-positive oligodendrocyte progenitors (B) co-expressed p-JNK. Many p-JNK-positive cells (C), RECA-positive endothelial cells (D) and O4-positive oligodendrocyte progenitors (E) expressed cleaved caspase 3. Scale bar = 25 μm. Inset scale bar = 2.5 μm.