IFNG and fibrosarcoma: In several other models, such as the use of the erythroleukemia cell line FBL-3 (25), the UV-induced fibrosarcoma 6132A-PRO (31), and the methylcholanthrene-induced Mc51.9 (32); no MHC class II was detected on tumor cells even after IFN-γ exposure, similar to MOPC315.