Fig 2: Upregulation of NID1 reverses the inhibitory effect of COL4A1 silencing on SCC-4 cells. (A) mRNA expression of NID1 in SCC-4 cells transfected with Oe-NID1 was measured via reverse transcription-quantitative PCR. ***P<0.001. (B) NID1 protein levels in SCC-4 cells transfected with Oe-NID1 measured using western blot assay. ***P<0.001. Cell proliferation in SCC-4 cells was evaluated using (C) Cell Counting Kit-8 (**P<0.01, ***P<0.001 vs. si-NC; ##P<0.01, ###P<0.001 vs. si-COL4A1+ Oe-NC) and (D) EdU incorporation (magnification, x100). (E) Colony formation assay (magnification, x1) was used to measure the colony-forming ability of SCC-4 cells. (F) Representative image of the wound healing assay of SCC-4 cells transfected with Oe-NID1 (magnification, x100). (G) Migration rate of SCC-4 cells transfected with Oe-NID1 measured using a wound healing assay. ***P<0.001. (H) Representative image of Transwell invasion assay of SCC-4 cells transfected with Oe-NID1 (magnification, x100). (I) Invasion rate of SCC-4 cells transfected with Oe-NID1 measured via Transwell invasion assay. ***P<0.001. (J) Protein levels of N-cadherin, vimentin and E-cadherin in SCC-4 cells transfected with Oe-NID1 semi-quantified using western blot assay. Results are presented as the mean ± standard deviation. **P<0.01 and ***P<0.001. NID1, nidogen-1; Oe, overexpression; NC, negative control; COL4A1, collagen type IV a1 chain; si, small interfering; OD, optical density.