More insights into the character differences between ChAT+ and ChAT- NK cells were obtained based on the gene-expression patterns. A clear delineation between ChAT+ NK cells and ChAT- NK cells was observed, with a total of 300 genes over-expressed and 941 genes under-expressed significantly in the ChAT+ subset. It will provide evidences for further investigation into their functional characters Overall design: NK cells from murine spleens were isolated by MACS sorting, and further purified into ChAT+ and ChAT- subsets based on ChAT-eGFP expression. The isolated ChAT+ or ChAT- NK cells from 2-4 mice were pooled into one sample to gain mRNA for microarray analysis. 4 samples from each group were acquired for expression profile analysis of the genes.