H2BC21 and neoplasm: Ex vivo biodistribution studies revealed a statistically significant linear correlation between tumor uptake of 111In-GFP-G1-TAT and expression of H2B-EGFP (Figs. 4A and 4B, r = 0.63, P = 0.004), demonstrating that 111In-GFP-G1-TAT can quantitatively determine the level of H2B-EGFP expression within tumor xenografts in vivo.