FGFR2 and Cutis gyrata - acanthosis nigricans - craniosynostosis: Indeed, Beare-Stevenson cutis gyrata syndrome, a genetic human condition caused by paralogous FGFR2 mutations, results in increased phosphoactivation of the FGFR2 effector substrate FRS226, itself a known p38-MAPK (and ERK1/2) substrate (albeit in relation to FGF1-mediated signaling)28,29.