Several genes involved in endocytosis play a role in membrane permeability. (A) ARP2, ARP3, and VRP1 are important for d-proline utilization. Cells of the indicated mutants and the corresponding complemented strains (ARP2, ARP3, and VRP1) were serially diluted and spotted on the indicated media. Plates were incubated at 30°C for 3 days and photographed. (B and C) Deletion of ARP2, ARP3, and VRP1 causes accumulation of different fluorescent dyes (B) or [3H]flucytosine (C). (D and E) Not every endocytic mutant accumulates different fluorescent dyes (D) or [3H]flucytosine (E). (ns, not significant [P > 0.05]; *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001; ****, P ≤ 0.0001).