To compare the endocytic uptake of exogenous PrP with the TAT PTD, we co-incubated murine N2a neuroblastoma cells with fluorescently-labeled recombinant murine PrP (rPrP)-546 (red) and TAT-Cre recombinase-488 (green) reporter proteins (Figure 1A, B). Here, PRNP is linked to neuroblastoma.