Yes, resistance and combinability are very important. And I believe simeprevir has been very good on both of these fronts. Look at prior combo data with sofosbuvir in nulls; data in combo with daclatasvir and also IDX719 due later this year and may still also be path forward in combo with Vertex's nuke, VX-135, particularly ex-U.S. Finally, there should be room to compete with competing sofosbuvir-based regimens on price, particularly given the significant amount GILD needs to recoup from its acquisition of VRUS.