Integrin 6 chain expression in CD4/CD8-defined thymocyte subsets in control or day 2, 4, and 6 P-Ir. Numbers represent the percentages found for 6⁻ (left region), 6ⁱⁿ (middle region), and 6^hi (right region) thymocytes. Values were obtained with the labeling of pooled thymocytes from at least three animals per point. Note: in this typical experiment, fluorescence intensities exhibited by subpopulations should be compared only for each day because thymocyte labelings were done on different days. Labeling with irrelevant antibody were done each day (not shown) and defined the negative region (left region) in the histograms.