Detection of Fas, FasL, and perforin mRNA using RT-PCR. PE-9 cells were stimulated with immobilized anti-CD3 MoAbs before PCR analysis. (A) PE-9 cells analyzed for FasL expression: lane 1, a molecular marker; lane 2, FasL; lane 3, β-actin (as a control). (B) PE-9 cells analyzed for perforin expression: lane 1, a molecular marker; lane 2, perforin; lane 3, β-actin. (C) FasL and perforin expression by tumor cell lines: lane 1, a molecular marker; lane 2, LSA tumor; lane 3, EL-4; lane 4, AutoD1.4T tumor. (D) Expression of Fas: lane 1, a molecular marker; lane 2, PE-9 cells; lane 3, LSA; lane 4, C57BL/6 thymocytes; lane 5, L1210 Fas⁻ cell line. (E) β-Actin controls for Fig 1D (lanes identical to those depicted in D).