Significantly, while exposure to bortezomib clearly downregulated HIF‐1β expression in various MM cell lines (eg, H929, RPMI8226, U266), ectopic ARNT overexpression, manifested by increased HIF‐1β protein level (Figure 2C, upper) and increased fluorescent signal in the nucleus (Figure 2C, lower; Figure S2C), promoted cell growth (Figure 2D) and reduced bortezomib lethality (Figure 2E). This evidence concerns the gene ARNT and Miyoshi myopathy.