VIP pretreatment-promoted long-term CE cell survival against the killing effect of severe oxidative stress (17 h, 1.4 mM H2O2). Amounts of genomic DNA derived from attached CE cells (0) increased and those from detached, free-floating CE cells (●) decreased in VIP-dependent manners. Relative amounts of genomic DNA derived from attached CE cells (0) in corneal cups that were pretreated with 0 (control), 10−12, 10−10, 10−8 and 10−6 M VIP, were, in %, (mean±sem [number of corneoscleral explants]) 100± 7 (8), 119± 11 (3), 152±15 (9), 140±9 (8), and 130±16 (7), respectively, and those of free- floating CE cells (●) were 100± 15 (8), 53± 22 (3), 62±13 (8), 30± 7 (9), and 28±11 (6), respectively. VIP-treated vs control significantly differed at p levels of < 0.05 (*), <0.005 (**), <0.002 (***), and <0.001 (****). Difference among treatments with varying VIP concentrations was significant (P<0.05, ANOVA) for both attached and detached CE cells. The amount of CE cell DNA in each corneal cup was normalized against the average of those found in the control corneal cups in each of the three separate experiments and the values were given on Y-axis.