Postnatally, Prop1:Cre;BrafV600E/+;RosaTM/+ (Prop1:Cre;BrafV600E/+ thereafter) pups showed clear signs of severe hypopituitarism with dwarfism and growth failure, and they died prematurely around weaning compared to their Wt littermates (Fig. 3a–c). This evidence concerns the gene PROP1 and hypopituitarism.