Figure 4.

(A) Following culture under hypoxia or normoxia, invasive cells were stained using Diff-Quik for counting. (B) The ratio of invaded cells was significantly increased by hypoxia compared with that under normoxia in HSC-2, HSC-4 and Ca9-22 cells (^*P<0.05). (C) To analyze whether hypoxia enhanced cell invasion through the Notch signaling pathway, cells were cultured with or without 5 μM GSI under hypoxia for 48 h. (D) GSI prevented cell invasion significantly in OSCC cell lines (^*P<0.05 and ^**P<0.01). These findings suggested that hypoxia promoted the invasiveness of OSCC cell lines through the Notch signaling pathway. GSI, γ-secretase inhibitor; OSCC, oral squamous cell carcinoma.