Reading this study http://www.nature.com/cr/journal/v23/n10/full/cr2013122a.html
Multiple exogenous and endogenous genes can be simultaneously activated by CRISPR-on
We tested single, double and triple activation of a TetO::tdTomato transgene and the endogenous SOX2 and IL1RN genes (Figure 3A) in HEK293T cells carrying the stably integrated TetO::tdTomato transgene
Could you please help me to understand: They talking about exogenous gene. But saying "carrying the stably integrated". Does that mean that this gene (TetO::tdTomato) is in the cell genome (integrated to genome)? If so, what is the meaning of exogenous here?