CTNNB1 and neoplasm: Moreover, a tumor mutational burden (TMB) analysis revealed that the overall TMB was significantly higher in RAB subtype-1 than in the other subtypes (Figure 3J), with mutations mainly originating from catenin beta 1 (CTNNB1), whereas the mutations in RAB subtype-2 and -3 were primarily derived from P53 (Figure 3K).