We tested the contribution of reduced protein synthesis activity to preleukemia progression by treatment with the S6K1 inhibitor (S6K1inh) PF4708671 (Fig. 6A), which impairs protein synthesis activity confirmed by reduced O-propargyl-puromycin (OP-Puro) incorporation in nascent peptide chains (Fig. 6, B and C). The gene discussed is RPS6KB1; the disease is myelodysplastic syndrome.