Kapα-facilitated turnover of Kapβ1 softens the NPC transport barrier against nonspecific cargoes. (A) Cartoon illustration of the experiment. (B) Kapβ1 turnover is coupled to a softening of the NPC transport barrier with Ran mix–activated transport. (C) Fluorescence quantitation after Ran mix shows that MG entry into the nucleus is marginally increased. n = 3 per experimental condition with a total of at least 13 cells being analyzed each. ****, P < 0.0001; Student’s t test. Box plots denote the median, first, and third quartiles. Error bars denote standard deviation, including outliers. Bars, 5 µm.