(A) Extraction of mRNA from neuroblastic tumour samples followed by RT-PCR using primers to detect both families of isoforms. (B) Relative amounts of VEGFxxx mRNA in neuroblastic tumour samples, NB and GN, represented as mean ± SEM. qPCR values were calculated in relation to expression of three reference genes (SDHA, HPRT I and β-actin). VEGFxxx was 3.54 times greater in malignant tumours than in benign tumours. (C) ELISA results on total VEGF and VEGFxxxb protein expression by different neuroblastic tumour samples showed as data points and median. Results normalized by protein. (D) VEGFxxxb relative expression decreases significantly with the malignancy of the tumour (unpaired t test, p<0.05). Mean ± SEM. (E) Immunohistochemical staining of VEGFxxxb and total VEGF in neuroblastic tumours. (F) Relative amounts of SRPK1 mRNA in NB and GN, represented as mean ± SEM. qPCR values were calculated in relation to expression of three reference genes (SDHA, HPRT I and β-actin). SRPK1 was 4.58 times greater in NB than in GN.