Notably, the immunostaining of HPSE was inversely or positively correlated with that of Smad4 (correlation coefficient R = −0.583, P < 0.001) and LEF1 (correlation coefficient R = 0.553, P < 0.001) in NB cases, respectively (Fig. 6a and Supplementary Table S2). This evidence concerns the gene SMAD4 and neuroblastoma.