During infection, JCPyV relies on usurping host-cell transcription factors to promote infection including NFAT, NF-kB, SMADs, Sp1, cJun, and cMyc [34,35,36,37,38,39], which are downstream of the MAPK-ERK signaling pathway, suggesting that JCPyV may reprogram host-cell transcriptional machinery through activation of the MAPK-ERK pathway. Here, JUN is linked to infection.