The very model of a modern art nonprofit, Pro Arts, founded in 1974, has served East Bay artists since 1979 as sponsoring organization for East Bay Open Studios. This year’s EBOS just concluded, having brought together 450 artists in thirteen cities, from Benicia to Livermore to San Leandro, with an estimated 50,000 viewers. It also provided workshops for artists on marketing and studio preparation, a gallery exhibition, a gala reception, and an art bus tour. In addition, Pro Arts maintains an ambitious exhibition schedule at its modern 2,500-square-feet gallery near Jack London Square — which includes a large space for traditional artworks and a dedicated PROJECT space for more experimental forms of work in new media, new genre, and installation — and at a satellite space in Oakland’s Latham Square, while its Gallery Store displays the artwork of member artists. Pro Arts is currently accepting proposals for installations and T-shirt and poster designs for this year’s Art & Soul Festival in downtown Oakland on Labor Day weekend.