“…These systems are highly conserved in vertebrates [ 1 , 2 , 3 ], where they regulate similar processes across taxa ranging from fish to amphibians to birds and mammals [ 4 ]. Their action is very diverse [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ], and both signalling pathways often cooperate in biological processes (e.g., during bone growth and differentiation [ 14 ], brain maturation [ 15 , 16 ], and liver metabolism [ 17 ]), where affecting one or the other signalling pathway results in various pathologies and developmental defects [ 5 , 18 , 19 ]. This is at the very heart of the biological question we ask, and we will list below some molecular details to highlight some sources of functional interactions between pathways.…”