Analysis of down-regulated genes at late time points compared with early time points reveals an early immune response in all cell lines. (A) Venn diagram showing the number of down-regulated genes (in parenthesis) at late, compared with early, passages in the R1, R3, R4, and R7 cell lines. (B) GO category enrichment performed on the common down-regulated genes in the R3, R7, R1, and R4 cell lines using FlyMine and Padj < 0.1.