Abstract: The invention provides a nucleic acid construct comprising a promoter sequence derived from microRNA-21 (miR-21) linked to a nucleic acid sequence encoding an anti-cancer agent, an example of which is a toxin. The constructs of the invention are particularly useful for treating tumors expressing miR-21.

Abstract: The present invention provides compositions and methods for light-activated cation channel proteins and their uses within cell membranes and subcellular regions. The invention provides for proteins, nucleic acids, vectors and methods for genetically targeted expression of light-activated cation channels to specific cells or defined cell populations. In particular the invention provides millisecond-timescale temporal control of cation channels using moderate light intensities in cells, cell lines, transgenic animals, and humans. The invention provides for optically generating electrical spikes in nerve cells and other excitable cells useful for driving neuronal networks, drug screening, and therapy.