The search for potential partners of human SELM in lysates of two cancer cell lines, HT-1080 (fibrosarcoma) and MCF-7 (breast adenocarcinoma), was carried out. Two cytoplasmic actin isoforms-cytoplasmic actin 1 (cytoskeleton beta-actin) and cytoplasmic actin 2 (cytoskeletal gamma-actin)-were identified as partners. In addition, the influence of two widely used antitumor selenium compounds (sodium selenite and methylseleninic acid) on the expression of SELM in cancer cells was studied. On the basis of the results obtained by real-time PCR and Western blotting, we concluded that 1 mu M and 10 mu M sodium selenite did not affect the expression of SELM in fibrosarcoma cells, whereas in breast adenocarcinoma cells 1 mu M sodium selenite slightly increased expression and 10 mu M sodium selenite significantly (approximately 2 times) decreased it. Methylseleninic acid in both cancer cell lines increased the SELM gene expression; the most pronounced effect was observed when fibrosarcoma cells were treated with 10 mu M MSA (the expression of the hSelm gene increased almost 4 times).