MLLT10 and neoplasm: Whereas B16K1 tumor growth was increased in vivo in ovariectomized (OVX) mice treated with E2 in all WT mice, the E2-induced tumor growth was completely lost in both the ERα-AF10 and ERα-AF20 mice (Figure 1B-C), demonstrating the crucial role of both the AF1 and AF2 transactivation functions of ERα for E2-induced tumor growth.