The cDNA was am- plified in 20-/xl reaction mixtures containing 0.2 /xM concentrations of corresponding primers, 0.5 U Taq polymerase (Perkin-Elmer Corp., Norwalk, CT), PCR buffer (Perkin-Elmer), and a 100 /xM dNTP mixture (Takara Shuzo Co., Ltd., Otsu, Japan), using a DNA ...