The invention stems from the discovery that sFRP and fragments thereof can bind to members of the Wnt family of proteins and cause an increase in Wnt biological activity. In a preferred embodiment, the parallel interface modem includes a modulation circuit for qualifying each of the plurality of parallel device interface signals for serial transmission. The packets of data are encoded using an encoding technique that provides unique codes that may be detected, thus enabling clock recovery of a clock signal embedded in the data packets. In addition, ailerons, a rudder and elevators may be provided for controlling roll, yaw and pitch during forward flight.