Figure 3. SEL-DEX inhibits the mTOR pathway.

MM.1S (GR^wt) and MM.1R (GR^null) cells were treated with 200 nM selinexor and 100 nM DEX for 24 hours. In MM.1S cells, selinexor alone had little effect on the mTOR pathway (p70S6K and p4EBP1). However, in combination with DEX, a significant reduction in p70S6K and 4EBP1 phosphorylation was seen. The phosphorylation levels of RPS6, downstream target of p70S6K, was also lowered more with the combination compared to the single agents. In MM.1R cells, the effect on the mTOR pathway was driven by selinexor with no effect from DEX.