MUC4 and neoplasm: Subcutaneously localized luciferase activity was identical in the two groups at the 2-hour time point, but at the 26, 30-day time point, there was a statistically significant increase in the bioluminescent signal in PANC-1-MUC4/Y-Luc cells compared to the negative control (Figure 5A), indicating that at the later stages, significant difference of tumor growth arised due to MUC4/Y-overexpression in vivo.