The effects of LPS pretreatment on the cisplatin-induced apoptosis of HIOEC and human OSCC cell lines. A. HIOEC and OSCC cell lines (5 × 105 ml-1) were pretreated with or without 1 μg/ml LPS for 4 h, then stimulated with 1 μg/ml cisplatin for 24 h. The cells were stained with Annexin V and PI and subjected to flow cytometry to determine the percentage of Annexin V+PI-/Annexin V+PI+ apoptotic cells. Results are representative of three independent experiments. B. As depicted, LPS significantly lowered cisplatin-induced apoptosis by elevating the resistance of OSCC cells but not HIOEC cells. (*p < 0.05, compared with the group treated with cisplatin only).