AZD 4573 and MC180295 (CDK9 inhibitors) in a dose-dependent manner were tested against a panel of 12 human MM cell lines (KMS11, MM1R, KMS12BM, H929, KMS18, 8226 LR5, MM1S, KMS11 res, 8226, KMS28, 8226 P100V, MM1S res) using an in vitro proliferation assay (MTT, 72 h). Here, CDK9 is linked to Miyoshi myopathy.