A. An external magnetic field drives magnetic carbon nanotubes toward a cell cultured on a polycarbonate filter. To indicate the molecular extraction, the cell is transfected for GFP overexpression beforehand. B. MCNTs spear into the cell under magnetic force. C. MCNTs spear through and out of the cell and extract GFP. GFP-carrying spears are collected in the pores of a polycarbonate filter. D. GFP representing the intracellular signal molecules can be used for analysis of individual pores.