NUCB1 and neoplasm: In striking contrast, tumors developed by ZR-75-1 cells expressing Hpa2-Nuc developed tumors that were 2.5-fold smaller than control (Fig. 2A; 0.21 ± 0.008 vs. 0.008 ± 0.001 g for Vo vs. Hpa2-Nuc, respectively; p < 0.001), implying that Hpa2 promotes, while nuclear localization of Hpa2 (Fig. 2B, left panels) restrains tumor growth.