Figure 3. USP4 expression significantly impacted HCC cell migration and invasion in vitro. (A) USP4 expression was aberrant in HCC cell lines, as compared to the normal liver cell lines L02 (* P < 0.05, ** P < 0.01). (B) USP4 expression was knocked down by lentivirus technology in SK-Hep1cells (** P < 0.01). (C) USP4 was overexpressed by lentivirus technology in HuH7 cells (*** P < 0.001). (D) Wound-healing assays detected the effect of USP4 knockdown on the healing ability of SK-Hep1 cells (*** P < 0.001). (E) Wound-healing assays detected the effect of USP4 overexpression on the healing ability of HuH7 cells (** P < 0.01, *** P < 0.001). (F) Transwell assays evaluated the effect of USP4 knockdown on the migratory ability of SK-Hep1cells (** P < 0.01). (G) Transwell assays evaluated the effect of USP4 overexpression on the migratory ability of HuH7 cells (** P < 0.01). (H) Matrigel invasion assays examined the effect of USP4 knockdown on the invasive ability of SK-hep1 cells (** P < 0.01). (I) Matrigel invasion assays examined the effect of USP4 overexpression on the invasive ability of HuH7 cells (** P < 0.01).