ITGA4 and gastrointestinal stromal tumor: Stratifying ITGA4 protein expression based on immunohistochemistry is subjective, but the immunohistochemistry scoring correlated with tumour ITGA4 mRNA qPCR measurements in a subset of cases, and showed associations with clinical parameters in a large clinical GIST series, suggesting that the scoring of the ITGA4 immunostainings reflected the sample ITGA4 content.