To confirm that NIP-2-H27A-N3 was able to engage the target, we performed a thermal shift assay in HeLa cell lysate. In this experiment, the peptide consistently led to a decrease in the melting temperature of NOT9 (Fig. , supplemental Fig. ). Although stabilization is commonly observed in such experiments, destabilization can also occur and in the case of NOT9 inhibition we speculate that this is due to the displacement of protein binding partners or RNA.