Fig. 9.

Diagram of potential functions of B7-H1 in cancer cell survival and chemoresistance. Overexpression of B7-H1 increases ERK activation through association with DNA-PKcs and leads to increased expression of survivin. B7-H1 deficiency decreased the activation of p38 MAPK that is dependent on the association of DNA-PKcs and B7-H1 followed by a downregulation of Bcl-2. Collectively, B7-H1 has a tumor-cell intrinsic pro-survival function and targeting B7-H1 signal pathways may sensitize cancer cells to chemotherapy.