ARNT and breast cancer: We established MCF-7 breast cancer subclones, which were stably transduced with lentiviral vectors encoding NTC shRNA or shRNA targeting HIF-1α (sh1α), HIF-1β (sh1β), or TAZ (shT1), and immunoblot assays confirmed effective knockdown of HIF-1α and TAZ [5] as well as HIF-1β (Figure 2A) protein expression.