ER EMSA (Electrophoretic-Mobility Shift Assay) kit is used for monitoring ER (Estrogen Receptor) DNA binding activities and activation. ER is a transcription factor involved in many cellular processes. Upon activation, ER can recognize and interact with the unique DNA binding sequence and form protein/DNA complex, which can be separated from free DNA due to the differences in their electrophoretic mobility in native (non-denaturing) polyacrylamide gels.