XIST and T-cell leukemia: We validated this approach by performing parallel RNA flow cytometry and qPCR on cell lines with known XIST expression levels: Jurkat, a male T cell leukemia line with low levels of XIST, and HEK293T, a female embryonic kidney cell line with high levels of XIST due to the presence of 2 inactive and 1 active X chromosomes per cell (36).