Analysis of the screens generated variable hit rates across the proteins with lysozyme yielding the highest number of crosslinking PhABits (47%), in contrast to myoglobin with very few binders (<3%) (Figure ). A number of warheads previously reported to bind to the proteins were identified as hits, including two dimethyl isoxazole fragments for BRD4-BD1 (see inhibitor iBET-151 ), and a series of sulfonamides for carbonic anhydrase (see dorzolamide, methazolamide and acetazolamide ). These hits provided early validation that the PhABit screen could identify true fragment binders.