KLF4 and periventricular leukomalacia: IHC staining of Sox2, Klf4, and Sox9 demonstrated that the number of Sox2+, Klf4+, and Sox9+ cells was increased in the PVL group of WT mice, but there was no significance in the numbers in TLR4-/- mice, and the positive cells were all located in the PV area (Fig. 5h), suggesting that LPS in the portal vein regulates the expression of pluripotent markers via the TLR4 pathway.