ERG and neoplasm: Therefore, we tested cells for ERG, ETV1, ETV4, or ETV5 expression, and found that ERG expression was upregulated in four clusters which we annotated as ERG-positive (ERG+ ) tumor cells (Fig. 2b and Supplementary Fig. 1a) but no cluster showed expression of ETV1, ETV4, or ETV5, suggesting that the six patients that contributed to these four ERG+ tumor cells harbored ERG fusion events.