MMP14 on target cells releases soluble TRAIL and is the third component that determines tumor sensitivity to HC/2G-1 T cells. (A) HEK-293 cells were transiently transfected with GFP expression plasmid, MMP14 expression plasmid, or DR4-expressing plasmid as indicated, and their recognition by HC/2G-1 was examined by IFN-γ ELISA. (B) Flow cytometric analysis of MMP14 expression on various cell lines. (C) CHO cell lines expressing GFP, TRAIL, TRAIL with MMP7, or TRAIL with MMP14 were prepared by lentiviral transductions. Each cell line was plated into 96-well plates (100 000 cells/well) and after an overnight culture, soluble TRAIL in the supernatant was measured using ELISA. (D) EBV-B cell lines were lent, virally transduced with GFP (white bars), MMP7 (gray bars), or MMP14 (black bars). Their recognition by HC/2G-1 was examined by coculturing overnight and measuring IFN-γ in the supernatant using ELISA.