FACS analysis of tumor cells from control (neo ) mice compared with cells from mice treated with gene-modified CL7.1 fibroblasts expressing CD40L. (A) and (B) Show upregulation of B7.2 and MHC class II on CD11a⁺ antigen presenting cells, while (C) shows upregulation of MHC class II on infiltrating CD3⁺ T lymphocytes. (D) Shows that there is no upregulation of fas on the surface of B220⁺ A20 cells in the presence of CD40L.