CCDC6 and cancer: Across all RET fusions, regardless of cancer types (Supplementary Fig. 6A, B) or fusion variants (Supplementary Fig. 6C–E), GC-rich sequences were found around the breakpoints of RET. For the common RET fusion partners, breakpoints in KIF5B, CCDC6 and NCOA4 most commonly occurred in exons 15, 1, and 7, respectively (Supplementary Fig. 6F–H), and were enriched with AT-rich sequences (Supplementary Fig. 6I–K).