NKX2.2 is a relatively new and valuable marker for ES, with a sensitivity of 93% and a specificity of 89%, and aids in the differential diagnosis of small round blue cell neoplasms.[30] The NKX2.2 gene was recently identified as a target of EWSR1::FLI-1, the fusion protein specific to ES, and was shown to be differentially upregulated in ES based on array-based gene expression analysis. This evidence concerns the gene FLI1 and Ewing sarcoma.