Because HDAC1 is a target gene of Sp1, and because the PI3K-Akt-Sp1 pathway was activated in MM cells in acidic conditions (Figure 3), we next investigated the role of the PI3K-Akt-Sp1 pathway in DR4 repression in MM cells in acidic conditions. This evidence concerns the gene TNFRSF10A and Miyoshi myopathy.