Fig. 2. Ubiquitin-specific peptidase (USP8) inhibitor suppresses anchorage-independent and dependent growth of gefitinib-sensitive HCC827 and gefitinib-resistant HCC827GR cells. (A) Whole cell lysates were assayed by western blot analysis using antibodies against epidermal growth factor receptor (EGFR), Met, and USP8. β-Actin was used as a loading control. (B) Colony formation of HCC827 and HCC827GR cells after exposure to the increasing concentration of USP8 inhibitor for 7 days. Random areas were scanned (five areas per well, three wells per set) in colonies grown in soft agar. Error bars represent the mean ± SD. Statistical significance was determined by the Student’s t-test (*P < 0.01). (C) Gefitinib-sensitive HCC827 or resistant HCC827GR cells were treated with various concentrations of indicated drugs for 3 days and cell proliferation was determined using the MTS assay. Error bars represent the mean ± SD. Statistical significance was determined by the Student’s t-test (*P < 0.01).

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