RAD21 plays multi-functional roles in cell. We explored which genes are target of RAD21 in the cell. We used microarray to find out the target of RAD21 comparing between shGFP(control) and shRAD21 expressing MCF7 cells. we stably expressed shGFP or shRAD21 in each MCF7 cell and selected single cells having high transfection efficiency of shRNAs. And then we had cultured the single cells for 30 days to harvest sufficient cells.