An analysis of HS1 protein in mixtures of BCL₁ cells and normal spleen cells. The percentage of BCL₁ cells mixed with spleen cells: lane 1, 0%; lane 2, 2%; lane 3, 5%; lane 4, 10%; lane 5, 20%; lane 6, 30%; lane 7, 40%; and lane 8, 50%. The arrow indicates the position of HS1 at 75 kD. The integrated optical densities of the HS1 band are as follows: lane 1, 5.6; lane 2, 5.9; lane 3, 10.8; lane 4, 10.6; lane 5, 18.9; lane 6, 26.2; lane 7, 37.1; and lane 8, 46.2.