Densitometric analysis of tyrosine-phosphorylated proteins in Ramos cells incubated with varying concentrations of high- and intermediate-affinity anti-IgM for 1 or 5 minutes. Ramos cells were stimulated as in Fig 10 in four separate experiments. The tyrosine-phosphorylated proteins designated p137, p96, p78, and p60 (see Figs 5 and 6) were densitometrically analyzed as described in Materials and Methods. The results are expressed as the percentage of the maximal anti-IgM–induced protein tyrosine phosphorylation observed for each protein at a given time point. The mean ± SD of the percentage of maximum values for the four separate experiments is shown, with the exception of data for cells incubated with the low (1 μg/mL) concentration of MoAb. This concentration was tested in only three of four of these experiments. The paired Student’st-test was used to evaluate the significance of the difference in protein tyrosine phosphorylation of a given protein elicited by high-affinity MoAb HB57 as compared with intermediate-affinity MoAb Mu53, at a given concentration. P (probability) values that approached or were less than P = .05 are indicated.