By 1905 Picasso became a favorite of the American art collectors Leo and Gertrude Stein. Their older brother Michael Stein and his wife Sarah also became collectors of his work. Picasso painted portraits of both Gertrude Stein and her nephew Allan Stein. Gertrude Stein became Picasso's principal patron, acquiring his drawings and paintings and exhibiting them in her informal Salon at her home in Paris. At one of her gatherings in 1905, he met Henri Matisse, who was to become a lifelong friend and rival. The Steins introduced him to Claribel Cone and her sister Etta who were American art collectors; they also began to acquire Picasso and Matisse's paintings. Eventually Leo Stein moved to Italy, and Michael and Sarah Stein became patrons of Matisse; while Gertrude Stein continued to collect Picasso.