BICD2 and infection: Because the retromer binding site and the CPP are also necessary during infection for stable exposure of the C-terminus of L2 in the cytoplasm where it can bind BICD2 [16,17,19,39,40], it is difficult to functionally dissect the previously identified roles those elements (i.e., retromer binding and cell-penetrating activity) from the role of BICD2 binding to this segment in infected cells.