CD274 and neoplasm: To further confirm our results, we assessed PD-L1 expression of RMS cell lines by two different techniques (flow cytometry and IHC on cytoblocks) and using two different clones of anti-PD-L1 antibodies: we were able to detect a very low percentage of tumor cells by flow cytometry, due to the high sensitivity of this technique, that accordingly was hardly detectable with a conventional IHC approach on FFPE cytoblocks.