Expression of Apo2L/TRAIL receptors and CD20 on cell lines. A panel of NHL cell lines and 2 control cell lines were stained with PE-conjugated antibodies to DR4, DR5, DcR1, and DcR2 (A) and CD20 (B). Data are reported as mean fluorescence intensity (MFI). The background fluorescence for the isotype control antibody on all cell lines was an MFI less than 6.