Fig. 6.

Effect of α4 transfection on the neurite outgrowth of PC12 cells. A, PC12 cell lines expressing α4α4 and α4α0 chains were surface-labeled with biotin and extracted with 1% Triton X-100. Immunoprecipitations were performed on equal amounts of protein with anti-human α4 antibody. Note that the full-length and truncated integrin are expressed at similar levels. Because the deletion only lacks 24 of the 999 amino acids in α4, no size difference would be expected at this resolution. α4 80 and 70 represent two products generated by post-translational cleavage of α4. B, Neurite outgrowth of PC12 cells stably transfected with α4α4, α4α0, or vector alone on 8V120, 8V95, and 8V0. Neurites were measured after 24 and 48 hr. In each experiment the neurites of at least 50 cells were measured, the median was determined, and the values normalized to control neurite outgrowth on 8V120 after 24 hr. Data represent the mean outgrowth at 48 hr of five separate experiments ± SEM. Note that the full-length, but not the truncated, α4 subunit restores increased neurite outgrowth of PC12 cells on V120-containing fragments (*p < 0.01).