Fig. 4.

iRin37-S319D cells are growth arrested and accumulate in G₀/G₁. (A) In the presence of serum, Cx37-WT and Cx37-S319D suppressed the proliferation of Rin cells; Cx37-S319A had no growth-suppressive effect. Error bars denote s.e.m.; *P<0.05 (one-way ANOVA with Tukey's post-hoc test). (B–D) In the presence of serum, the percentage of Cx37-S319D cells in G₀ or G₁ (labeled G₁) increased as the percentage in G₂ decreased, suggesting that cells in G₂, when CX37-S319D expression was initiated, were able to complete the cell cycle and were subsequently arrested in G₀ or G₁. (E) Serum deprivation arrested proliferation in an isoform independent manner. (F–H) All phases of the cell cycle were extended in Cx37-WT expressing cells, with no significant increase in any phase over the 5-day period. In contrast, the percentage of S319D cells in G₀ or G₁ increased while simultaneously the percentage in both S and G₂ decreased significantly, suggesting that S and G₂ cells are able to complete the cell cycle and arrest in G₀ or G₁. The Cx37-S319A cells also accumulate in G₀, but for this isoform the percentage in S decreases substantially while G₂ percentage is constant. All error bars denote s.e.m.; *P<0.05 between day 1 vs 5, P values stated in text.