The human Arg (Abl2) nonreceptor tyrosine kinase has a role in cytoskeletal 
rearrangements by its C-terminal F-actin- and microtubule-binding sequences. We 
have previously identified Arg transcripts with different 5'- and 3'-ends, named 
respectively long and short 1A and 1B (1AL, 1AS, 1BL, 1BS) and long and short 
C-termini (CTL and CTS), that have different expression patterns in various cell 
types. The combination of the different ends permits to predict eight putative 
full-length Arg transcripts and corresponding proteins. By Reverse 
Transcription-Long PCR we show here that all eight full-length transcripts are 
endogenously expressed in Caki-1 cells and the two bands, approximately 10 kDa 
different, shown by 1-D Western blots of Hek293T and Caki-1 lysates correspond 
to the full-length Arg protein isoforms with different C-termini. 2-D Western 
blot analysis evidenced different high molecular weight and slight acidic 
specific spots in Hek293T and Caki-1 lysates. The cellular localization of two 
Arg isoforms (1BLCTL and 1BLCTS) transfected in Caki-1 and Hek293T cells was 
cytoplasmic, and some differences in cytoskeleton interactions have been 
evidenced. Moreover, in Hek293T cells only the transfected 1BLCTS isoform gives 
rise to a large intracytoplasmic cylindrical structure containing 
phalloidin-positive amorphous actin aggregates. The presence of eight 
full-length Arg isoforms with different cellular expression may imply a diverse 
functional role in normal and neoplastic cells.