PGP and Miyoshi myopathy: On the other hand, a new study on MM cell biology and pathogenesis identified a chromosomal instability (CIN) gene called NEK2 whose overexpression upregulated MDR-related proteins, MDR1 (P-gp), MRP1 and BCRP and was strongly associated with resistance to drugs (bortezomib and doxorubicin), rapid relapse and poor outcome in MM [105].