Overexpression of SPARC and low-dose radiation in NB1691 and SK-N-BE(2) subcutaneous tumors suppresses tumor growth. Time line showing neuroblastoma tumor implantation and SPARC treatment with or without radiation in nude mice (A), 45 days after tumor development, tumors were harvested and volumes were measured (B). (C) (SKC, SK-N-BE(2) control; SKCR, SK-N-BE(2) + 5 Gy radiation; SKSP, SK-N-BE(2) + SPARC overexpression; SKSPR, SK-N-BE(2) + SPARC overexpression + 5 Gy radiation; NBC, NB1691 control; NBCR, NB1691 + 5 Gy radiation; NBSP, NB1691 + SPARC overexpression; NBSPR, NB1691 + SPARC overexpression + 5 Gy radiation). (D) After formalin fixation the tumors were processed for paraffin sectioning and VEGF-A and SPARC expression levels were visualized by immunohistochemistry.