A Beverly Hills, 90210 reunion happened over the weekend! Brian Austin Green, who played David Silver in the show, just turned 50 and celebrated with a few familiar faces. Shannen Doherty (Brenda Walsh) came to party amid her battle with stage four breast cancer. She shared a few photos on Instagram and sent her birthday wishes to Green. Their former co-star Ian Ziering (Steve Sanders) also joined in on the festivities.