Objective Voltage-gated sodium channels are commonly expressed in "excitable" cells, such as neurons and muscle cells, but an increasing evidence showed that a variety of cancer cells expressed VGSCs which involved in metastasis of the cells.Previous studies showed that human breast cancer MDA-MB-231 cells expressed SCN5A (Navl.5 subtype) of VGSCs and Tetrodotox,an inhibitor of VGSCs,could suppressed the mi-gration of MDA-MB-232 cells.The present study is to investigate the RNAi effects target-ing SCN5A gene on migration and invasion of human breast cancer MDA-MB-231 cells.