Fig. 1. USP24 positively regulates drug resistance.

The levels of USP24 in A549 cells and the drug-resistant cell lines A549-T24, A549-CPT-R, and A549-CDDP-R cells were determined by Western blotting (A, C, E). The cytotoxic effects of Taxol, CPT, and CDDP in normal and drug-resistant A549 cells with or without USP24 knockdown were studied (B, D, F). A549 cells with or without USP24 knockdown were treated with Taxol for three months, and the IC₅₀ of Taxol in the cells was determined (G). T24 cells with or without USP24 knockdown were injected into NOD/SCID mice, and the mice were subsequently injected with Taxol at the indicated times. Tumor volume was determined (H). The results from three independent experiments were statistically analyzed using a t-test: *p < 0.05, **p < 0.01, ***p < 0.005.