ACVR1 and cancer: Similarly, TP53 is almost exclusively mutated in the H3.3 group, again explaining mutually exclusivity between TP53 and ACVR1. All these candidates, together with the mutually exclusive TP53-HIST1H3B pair, were also found in the PAN cancer test, due to this strong signal in HGG-K27M, rather than similar patterns in other cancer types.