SLC51B and periventricular leukomalacia: We found that compared with the PVL group, an earlier and stronger up-regulation of FXR expression was observed in the BPL group (Fig. 2B,D), which is accompanied by prompt and sustained repression of transcription of CYP7a1 and NTCP, and more marked and drastic up-regulation of BSEP and OSTβ (Fig. 2E).