PRV-1/GAPDH ratios of patients with PV and SE, and of healthy controls. The mean PRV-1/GAPDH ratio of 61 patients with PV-WHO, 7 patients with PV-PVSG, 7 patients with SE, and 61 healthy controls is shown together with the 95% confidence interval of the mean. The significance of the difference of the means was assessed by the Kruskal-Wallis analysis of variance on ranks and the Dunn method for pairwise multiple comparisons.