IntClusts 2 and 6 are relatively small subgroups comprising ER+ cancers with poor outcome, but MAP3K1 mutations in IntClust2 (median=1, IQR=0.91–1, seven mutations) were present in higher CCFs than in IntClust6 (median=0.90, IQR=0.69–0.99, six mutations). This evidence concerns the gene MAP3K1 and cancer.