Cell recovery of primary ALL cells after culture on mesenchymal cell layers according toCASP8AP2expression. Primary ALL cells, selected from cases with known CASP8AP2 levels by GeneChip, were cultured on confluent mesenchymal cells for 7 days in serum-free medium. The number of viable ALL cells recovered at the end of the cultures was compared with the number of cells originally seeded. The dashed line indicates median cell recovery for the 24 cases. P value was calculated by Wilcoxon 2-sample test.