When PTEN null or PTEN overexpressing myeloma cells were injected into SCID mice, all PTEN null mice developed tumors, while only 50% of those injected with PTEN overexpressing MM cells developed tumors, which were additionally both smaller and required longer than 5 times the latency period of controls for formation [3]. The gene discussed is PTEN; the disease is Miyoshi myopathy.