FOXO3 and neuroblastoma: Interestingly, the response of the PKB - FOXO3 signaling pathway to chemotherapeutic drugs used in the therapy of NB strongly differed between the three chosen cell lines SH-EP which represents a stromal phenotype, STA-NB1 (stage III) and STA-NB15 (stage IV): whereas in SH-EP and STA-NB1 cells FOXO3 phosphorylation was reduced during drug-treatment, in STA-NB15 cells PKB-signaling remained constant and FOXO3 steady state levels as well as phosphorylation strongly increased (Figure 2C).