Short form products of the MEL1 gene were expressed in ATL cell lines. (A) Transcription of MEL1 and MEL1S genes. The transcription of MEL1 and MEL1S genes were studied with the specific primers in ATL cell lines and control cell line as follows: lane 1, 293 cells; lane 2, MT-4; lane 3, ATL-35T; lane 4, ATL-43T; lane 5, ATL-55T; lane 6, ED; and lane 7, ATL-2. RT-PCR that could detect both MEL1 and MEL1S gene transcripts revealed the transcription (330 bp) in all cell lines, whereas RT-PCR with primers specific for MEL1 gene detected the transcript (197 bp) only in 293 cells. (B) Western blot analysis of MEL1 and MEL1S. Cell lysates were analyzed by Western blot using antibodies against the MEL1/1S protein. Lane 1, ATL-55T; lane 2, ED; and lane 3, 293 cells.