Known especially for his caricatural drawings and paintings of Berlin life in the 1920s. He was a prominent member of the Berlin Dada and New Objectivity group during the Weimar Republic. He emigrated to the United States in 1933, and became a naturalized citizen in 1938. Abandoning the style and subject matter of his earlier work, he exhibited regularly and taught for many years at the Art Students League of New York. In 1956 he returned to Berlin where he died.