KN-62 inhibits ATP-induced shedding of CD23 and L-selectin. B-CLL lymphocytes were treated with the indicated concentrations of KN-62 before exposure to 500 μmol/L ATP (7 minutes for CD23 and 1.5 minutes for L-selectin measurements). Cells were then labeled with anti-CD23 (○) or anti–L-selectin (•) and the results expressed as the mean percentage of inhibition of shedding (difference of means not significant, n = 3).