Mariachi music and musicians became more professional with more formal training starting in the late 1940s and early 1950s, principally due to the success of a major mariachi by the name of Mariachi Vargas. Their appearance in many films, backing many singing stars, and their hiring of formal musicians prompted other mariachis to do the same. The group also expanded, adding trumpets, violins and even a classical guitar to become a kind of orchestra, keeping the traditional "son"/mariachi base while integrating new musical ideas and styles. One other innovation, in contrast to the machismo of the style, were the first female mariachi performers, Lola Beltrán and Lucha Villa. One night Mariachi Vargas put Beltrán on stage when she was a teenager. Her versions of "Cucurrucucu Paloma" and "Tres Dias" are now considered classics.