We previously reported that miR-199a-5p upregulates mTOR signaling activity by repressing the expression of mTOR signaling inhibitors, including Sirtuin-1, hypoxia-inducible factor 1 subunit alpha, and Pde4d. 8In the present study, we further confirmed that PDE4D functions as a downstream target of miR-199a-5p in MDS model neurons, supporting its involvement in mTOR pathway dysregulation in this context. Here, SIRT1 is linked to myelodysplastic syndrome.