Although, we have not screened for these mutations in our MM cell lines, our U266 cell line has shown deletions of chromosome 13 and 17p, which involve, respectively, RB1 and TP53 genes, whereas RPMI-8226 cell line has shown neither deletion of chromosome 13, nor deletion of chromosome 17p (Figure 1). This evidence concerns the gene RB1 and Miyoshi myopathy.