The present invention provides the enzyme and enzymatic procedures for cleaving the \u03b2 secretase cleavage site of the APP protein and associated nucleic acids, peptides, vectors, cells and cell isolates and assays. The string includes a polymer cover that protects the string, from contamination while maintaining the original lively sound of the musical string. The microprocessor converts sensor inputs from the foot-operated controller into commands for a controllable electromechanical device such as a prosthetic hand. Also disclosed are methods of enhancing muscle regeneration, repair, or maintenance in a subject and methods of enhancing \u03b17\u03b21 integrin expression by use of the disclosed \u03b17\u03b21 integrin modulatory agents.