Observations in vivo and in vitro demonstrate: 1) smooth muscle cells are capable of more
than one function and can alter their phenotype/state accordingly (modulation); 2) in the
majority of cases before a smooth muscle cell can divide it must modulate from a contractile
to a synthetic phenotype; 3) modulation is reversible; 4) however, if synthetic state smooth
muscle which has been stimulated to divide achieves approximately nine cell doublings
before being inhibited by confluence it appears unable to return to the contractile state; 5) …