MFPs are involved in successive or parallel processes. If the amount of MFPs is not limited in the cell, they can be involved in multiple subsequent steps within one biological cascade (a). An example for this is Pex3p. In addition MFPs can promote two pathways simultaneously (b). As discussed in the text, the two parallel pathways may later converge onto a common purpose like promoting cell proliferation (this can be the case for Cdk7).