Reply: Comment on: Notch-1 and Notch-3 mediates hypoxia-induced synovial fibroblasts activation in rheumatoid arthritis.

We appreciate the comments from Dr. Wang-Dong Xu et al. It has been confirmed that hypoxia-inducible factor 1α (HIF-1α) regulates the expression of Notch-1 in Rheumatoid arthritis (RA) synovial fibroblast cell (RASFC) under hypoxia(1). Furthermore, our study shows that HIF-1α directly regulates the expression of Notch-1 and Notch-3 in the hypoxic microenvironment(2). However, for cells to adapt to the hypoxia microenvironment, HIF-1α and Notch signal transduction regulate each other.