The expression level of miR-221/222 is negatively correlated with the melphalan sensitivity of MM cells, and miR-221/222 inhibition restores melphalan sensitivity and triggers apoptosis of MM cells with upregulation of proapoptotic Bcl-2-binding component 3 (BBC3)/PUMA, modulation of drug influx–efflux transporters SLC7A5/LAT1, and the ATP-binding cassette transporter multidrug resistance-associated protein 1 (ABCC1/MRP1) (52). The gene discussed is ABCA4; the disease is Miyoshi myopathy.