Different fragments were identified as hits for each sequence pointing to the specificity of the selection process. For validation, a competition assay for ten hits was carried out (highlighted in the orange box in Fig. , supporting information for additional results, Fig. ). Fig. illustrates IC50 data for four hydrazone hits that exceeded affinities of hDMX361-374 pSer367 * and the control hydrazide peptide (note: the steep Hill slope for the first derivative may suggest the boronic acid plays a role in covalent modification).