The GENIA tagger (Tsuruoka et al., 2005) is particularly relevant in this respect (as could be the GENIA Treebank proper 4 ).
we found that GENIA tokenization does not match the PTB conventions in about one out of five sentences (for example wrongly splitting tokens like '390,926' or 'Ca(2+)'); also in tagging proper nouns, GENIA systematically deviates from the PTB.