DLL1 and infection: The transcription factor gene rbpjκ and E3 ubiquitin ligase gene dtx1, which play important roles in Notch pathway activation and regulation, were upregulated at 48 and 72 h p.i. Only a small percentage of genes were downregulated during the infection, including genes for the Notch pathway components dll1 and mmp7 (Fig. 2A).