A pharmaceutically acceptable composition and method for entering a cell
nucleus utilizes a cell nucleus-entering polypeptide including at least
one of amino acid sequence LKKTET (SEQ ID NO:1), amino acid sequence
LKKTNT (SEQ ID NO:2) or amino acid sequence KSKLKK (SEQ ID NO:3), or a
conservative variant thereof, linked to a physiologically active agent
having at least one of therapeutic or diagnostic application in the cell
nucleus.