ULBP2 and infection: In addition, the observations that infection with the HMPV/ΔG virus increases the protein levels of ULBP2 and that ULBP2 is further upregulated in the presence of lysosome inhibitors, suggest that HMPV, via its viral protein G, contributes toward downregulating the surface expression of ULBP2, likely through the lysosomal pathway.