EPIDERMAL GROWTH-FACTOR INDUCES SERINE PHOSPHORYLATION OF ACTIN

Stimulation of cells by epidermal growth factor induces a rapid polyme risation of actin in the cortical skeleton. Activation of the EGF-rece ptor leads to autophosphorylation and to phosphorylation of specific i ntracellular substrates. Here we show that actin is phosphorylated in vitro and in vivo upon EGF stimulation. Two-dimensional phospho-amino acid analysis shows that phosphorylation occurs on serine, not on tyro sine residues.