ERAP1 and infection: Additionally, other members of the peptide-loading complex, TAP1, TAP2, tapasin (TAPBP), calreticulin (CALR), ERP57 (PDIA3), and ERAP1 (required for peptide trimming), were all significantly upregulated during the clearance phase of infection (Fig. 4A); Tap1 was significantly transcriptionally upregulated at 10 to 20 DPI (Fig. 4B), while the MHCI protein H2-D1 showed a modest transcriptional increase at 10 to 13 DPI (Fig. 4C).