CTNNB1 and neoplasm: Two mutations (p.S33P and p.S37P) that share a trinucleotide context and an amino acid substitution that blocks Gsk3β phosphorylation18,22 had different mutational patterns: p.S33P was exclusive to the KrasG12D cohort (found in 10 out of 147 Ctnnb1-mutant tumours), while p.S37P had a broad distribution and positive O/E ratio (Fig. 2a,c–e).