To investigate the role of PIAS1 as a SUMO E3 ligase on metastatic tumor and growth potential in vivo, we determined the effect of expression of the SUMO E3 ligase PIAS1 (CS) mutant in the MDA-MB-231-Luc cells on their ability to form osseous metastases. This evidence concerns the gene PIAS1 and metastatic neoplasm.