( ( For example ) ( , ( it ( ( plays ( ( a ( key role ) ) ( in ( the ( developing ( nervous system ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN For) (NP (NN example))) (, ,) (NP (PRP it)) (VP (VBZ plays) (NP (NP (DT a) (JJ key) (NN role)) (PP (IN in) (NP (DT the) (VBG developing) (JJ nervous) (NN system))))) (. .)))
For example, it plays a key role in the developing nervous system.
(ROOT (S (NP (DT The) (JJ nervous) (NN system)) (VP (VBZ plays) (NP (NP (DT a) (JJ critical) (NN role)) (PP (IN in) (NP (NP (DT the) (NN regulation)) (PP (IN of) (NP (NN vascular) (NNS homeostasis))))))) (. .)))