Therefore at one day post infection (and only at this time of infection), the particular gene-expression signature observed in infected mice was dependent on the upregulation of PC2 genes, and downregulation of Rxra. Rxra codes for Retinoid X Receptor Alpha (RXR-α), a nuclear receptor that mediates the biological effects of retinoids by binding, either as homodimer or heterodimer, to specific sequences in the promoters of target genes (Figure 5B). The gene discussed is RXRA; the disease is infection.