Transient RARRES2 overexpression inhibits cell proliferation in HEK293 cells and leads to reduced cellular invasion in H295R and HEK293 cells. (a) Baseline RARRES2 and CMKLR1 gene expression levels were barely detectable in the cell lines tested using TaqMan qPCR. (b) The time course for RARRES2 expression after transient transfection in HEK293, H295R and SW13 cell lines. (c) in vitro cell proliferation curve for cell lines transiently transfected with a vector control or RARRES2. Transient overexpression of RARRES2 inhibited cell proliferation in HEK293 cells, but not in H295R or SW13 cells. Data were presented as mean ± SEM. *, P < 0.0001. (d) Transient RARRES2 expression inhibits cellular invasion in H295R cells and HEK293 cells but not in SW13 cells. *, P < 0.05; **, P < 0.01; ns, not significant. (e) Transient RARRES2 expression does not affect cell migration. No significant difference was observed between cells transfected with vector or RARRES2.