BASEL, SWITZERLAND.- Jen Lissitzky has filed suit in Basel against the Beyeler Foundation there, seeking to recover a painting by Wassily Kandinsky that was looted by the Nazis in 1937. The painting, Improvisation No. 10 (1910), was owned by Lissitzky's mother, Sophie Küppers-Lissitzky, and taken by the Nazis from the Provincial Museum in Hannover as part of its "Degenerate Art" campaign. Swiss dealer and collector Ernst Beyeler purchased the work in 1951 in Cologne from Ferdinand Möller, one of Hitler's art dealers, in a shady transaction that Beyeler himself has admitted; the painting still has the Nazi inventory number on its reverse side. The court action follows the breakdown of mediation proceedings in November. The lawsuit, which is handled by New York art lawyers Lawrence M. Kaye and Howard N. Spiegler, is the first court test in Switzerland of the 1998 Washington Conference Principles on Nazi-Confiscated Art, which urged the return of stolen cultural property from the World War II era.