ISL1 and neoplasm: Tumor size was measured on the indicated days after injection, and the tumor volumes formed by the ISL1-overexpressing cells were significantly larger than that of the control cells at day 21 (1.56 ± 0.73 cm3 vs. 0.35 ± 0.21 cm3, p < 0.05) (Figure 3A, 3B).