Distribution of β-tubulin class II in tumor and normal tissue samples. (A) Fractions of β-tubulin class II ranked in descending order. Tumor and normal samples are designated as in Table 1. The fraction of β-tubulin class II was calculated as the proportion of the total tubulin, including β-tubulin classes I + IV and III. The distribution was similar when β-tubulin class III was not included (data not shown). (B) Frequency distribution for all data in (A). Gaussian fits of the data are superimposed: solid line, all data; broken line, normal tissue; dotted line, tumor tissue. The mean fraction of β-tubulin class II in tumor tissues is 0.60 ± 0.10 and for normal tissue it is 0.56 ± 0.07. Student t-test comparing the normal and tumor tissue data showed no significant difference (t = -1.45429, P = 0.15).