RASopathies, such as cardio-facio-cutaneous (CFC) syndrome and Noonan syndrome, are rare developmental diseases caused by germline mutations that lead to overactivation of the RAS-MAPK pathway. Anastasaki et al. build on previous work to test whether fine-tuning doses of PD0325901, an inhibitor of this pathway that is in clinical use for cancer treatment, can minimise the developmental defects of RASopathies. Using zebrafish embryos, they show that continuous, low doses of PD0325901 during development prevents the detrimental effects of a CFC-associated mutation without inducing the side effects observed when inhibiting the pathway using higher doses of the drug. Thus, anti-cancer agents that target the RAS-MAPK pathway might hold promise for these devastating developmental diseases. Page 546

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