Hypoxia-inducible factor-1α–mediated upregulation of CD99 promotes the proliferation of placental mesenchymal stem cells by regulating ERK1/2

Figure 6 Hypoxia-induced CD99 expression modulates human placenta-derived mesenchymal stem cells proliferation via the MAPK/ERK signaling pathway. A: Western blotting of phosphorylated (p)-ERK phosphorylation in human placenta-derived mesenchymal stem cells (hP-MSCs) exposed to hypoxia for 48 h and pretreated with siCD99#1; B: Immunofluorescence microscopy of (p-ERK) in hP-MSCs cultured under hypoxia for 48 h and pretreated with siCD99#1 (× 20 magnification; scale bars, 50 μm); C: Western blotting of cytoplasmic and nuclear fractions of hP-MSCs cultured under hypoxia for 48 h and pretreated with siCD99#1. p-ERK expression was normalized against that of ERK or histone H3. Data are means ± SD (n = 3). ^aP < 0.05 and ^bP < 0.01. OD: Optical density.