PIK3CB and thymoma: We found significant enrichment of mutated genes in both the RAS (q=7E-8) and PI3K-Akt signaling pathways (q=2E-7), including AKT3, CSF1R, FGFR4, KRAS, NRAS, PIK3CA, and PIK3CB (Figure 1 and Supplementary Table 4), and those mutated genes were mainly enriched in thymoma samples, suggesting that RAS and PI3K-Akt signaling pathways may involve in the tumor development of thymoma.