Fig. 3.

Cx37-S319A alleviates whereas -S319D enhances Cx37 mediated growth arrest. (A) Proliferation of expressing (dox+) and non-expressing (dox−) iRin37-S319A clones and iRin37-WT (n=3 for each) did not differ over 21 days (P=0.1582); only for Cx37-WT do the dox+ and dox− curves differ (P<0.0001), indicating lack of growth suppression by the -S319A mutant. The semi-log plot of these data (inset) shows that non-expressing iRin37-WT and both expressing and non-expressing iRin37-S319A mutant cells proliferate at comparable rates, whereas WT-expressing cells do not proliferate. *P<0.0001 significantly different from non-expressing (dox−) cells; ns, not significantly different. (B) The proliferation of iRin cells expressing Cx37-S319D or Cx37-WT is comparable and significantly (*P<0.0001) reduced compared to non-expressing cells of the same clone (n=3 for each). Inset, semi-log plot of proliferation over 6 days (n=3) showing that cell number increases, but does not double, in iRin37-S319D cells. ^†P=0.0024 from WT; ns, not significantly different. (C) 21-day proliferation curves in which Cx37-WT or -S319D expression was induced with dox on day 12 (n=3 for each clone) show suppressed proliferation at higher cell density (than in B). Inset, semi-log plot and regression analysis showing slowed proliferation after versus before induced expression of both Cx37-WT and Cx37-S319D isoforms. *P<0.05 from dox− growth period (2C1 P=0.0026; 2B7 P=0.0229; WT P=0.0024); ns, not significantly different. Double headed arrows in C indicate the period of dox exposure. All error bars denote s.e.m.; statistical differences were assessed using linear regression analysis.