Percoll density gradients were fractionated (eight fractions; fraction 8 is the bottom of the gradient and fraction 1 is the top of the gradient), the fractions were separated by SDS/PAGE [16% polyacrylamide for the NTF of MT-SP1/matriptase (MT-SP1NTF) and 12% polyacrylamide for alkaline phosphatase (ALK Phos), Na,K-ATPase and E-cadherin] and the Western blots were probed with Tmc172, anti-alkaline phosphatase antibody, anti-Na,K-ATPase antibody and anti-E-cadherin antibody respectively. The most intense signal in a fraction was given the value of 100%. The results are the means±S.D. for six different preparations.