Four kinds of human tumor cell lines were transfected by three kind of vector constructs (the empty vector: pcDNA3.1 (Mock); pcDNA3.1-rps4 bearing Dictyostelium cytoplasmic ribosomal protein S4; pcDNA3.1-mrp4 bearing Dictyostelium mitochondrial ribosomal protein S4). This evidence concerns the gene RPS4X and neoplasm.