Fig. 6.

Exogenous SLPI inhibits cell growth and induces apoptosis activities in E6 positive HNSCC cells. a, b MTT assay revealed that exogenous SLPI significantly suppressed HPV E6 positive or E6 negative HNSCC cells proliferation. c, d Exogenous SLPI affected the cell distribution in HNSCC cells with or without E6 expression, mainly manifested by decreasing cells in S phase and increasing cells in G1 phase. e, f Apoptosis assay results suggested that apoptosis resistance of E6-expressing HNSCC cells was functionally reversed by SLPI treatment *P < 0.05. **P < 0.01. ***P < 0.001