Fig. 5. Mrj is required for proteasome degradation of keratin filaments. (A) Expression of Mrj (red) and 20S proteasome core subunits (green) in wild-type trophoblast giant cells in vitro. (B) K18 expression (green) in trophoblast giant cells cultured with (right) or without (left) the proteasome inhibitor clasto-lactacystin ß-lactone. (C) Mrj expression (red) in trophoblast giant cells treated with clasto-lactacystin ß-lactone. K18 is green. (B,C) DNA is blue. Scale bars: 10 µm.