Min Q, et al. - Co-expression of constitutively active S127A-YAP1 and ΔN90 deletion-mutant β-catenin (YAP1–ΔN90-β-catenin) in mice causes hepatoblastoma (HB), the most common pediatric primary liver neoplasm. Because heterogeneity is identified in downstream signaling due to mutational differences even in the β-catenin gene alone, researchers examined whether co-expression of β-catenin point mutants (S33Y or S45Y) with S127A-yes-associated protein 1 (YAP1) resulted in similar tumors as YAP1–ΔN90-β-catenin. Using a previously reported 16-gene signature, YAP1–ΔN90-β-catenin HB tumors showed genetic similarities with more proliferative, less differentiated, glutamine synthetase (GS)-negative HB patient tumors. On the other hand, YAP1–S33Y/S45Y-β-catenin HB showed heterogeneity and clustered with both well-differentiated GS-positive and proliferative GS-negative patient tumors. Thus, the investigators show that β-catenin point mutants can also collaborate in HB development with YAP1, although with a distinct molecular profile from the deletion mutant, which can have implications in both biology and therapy.