S100A4 and pachyonychia congenita: To further validate our results, a web based analysis was performed using R2: Genomics Analysis and Visualization Platform (http://r2.amc.nl/), which revealed a significant correlation between S100A4 gene expression and overall survival of patients with PC (Figure 5, P < 0.02 for high versus low expression, expression cutoff: 152.1 [minimal group = 8]).