BIRC5 and Miyoshi myopathy: BIRC5 expression in primary MM cells correlates significantly with proliferation as assessed by the gene expression profiling derived proliferation index, GPI (r = 0.81, p < 0.001) or propidium iodide staining [2] (r = 0.59, p < 0.001; n = 36), and the expression is significantly different between a low/median/high GPI (Figure 1A).