PHOX2B and osteosarcoma: In contrast, MONC-1 cells gave rise to various tumor types, as 3/7 mice developed osteosarcoma with chondrosarcoma components (Figure 1D), 1/7 mouse developed a highly malignant Phox2b−/nestin+ undifferentiated tumor (Figure 1E), and 3/7 mice developed Phox2b+/Th−/nestin− undifferentiated NB (Figure 1F).