Formation of striated muscle from myoblasts in vitro: inhibition of myotube formation by cis-4-hydroxy-L-proline and its reversal by native or denatured collagen (gelatin).

Previous efforts to define the nature of the complex requirements for the development of striated muscle in vitro led us to the finding that the presence of collagen in the extracellular environment is essential for the formation from myoblasts of the multinucleated myotube (1). In the present report we demonstrate that the proline analog, cis-4-hydroxy-L-proline, will inhibit myotube formation in vitro without affecting the aggregation of cells (fusion?). The presence of collagen or gelatin as a culture substratum overcomes the action of the analog. The role of collagen in the development of the myotube is discussed.