Retroviral expression of Delta4 protein.

Cell extracts were prepared from NIH3T3 cells transduced with pMSCVpac, pMSCVpacDelta4, MigR, or MigRDelta4. Expression of Delta4 was detected by Western blot analysis with polyclonal anti-Delta4 antibodies in cells transduced with Delta4-carrying virus but not control virus. Delta4 in MigR was fused to a C-terminal myc tag and could also be detected with anti-myc monoclonal antibodies (mAbs).