Fig. 7.
ATP release from Cx23 expressing HeLa cells. (A) Two independent clones for Cx23eGFP and Cx23-IRES-eGFP were tested for release of ATP and adjusted to their expression level via Western blot analyses for eGFP. The combined data from Cx23eGFP- and Cx23-IRES-eGFP-expressing HeLa cells showed release of significantly higher amounts of ATP into the extracellular medium relative to HeLa parental cells (p23eGFP = 0.018; p23IRES = 0.004). Zero extracellular calcium concentration leads to a weak, statistically non-significant increase in ATP release in Cx23-expressing HeLa cells (p23eGFP = 0.1, p23IRES = 0.36). (B) Increased expression of Cx23 in different Cx23-IRES-eGFP HeLa cell clones led to an elevated release of ATP (clone K19 versus K18). (C) As an approximation for the expression level of Cx23 in different Cx23-IRES-eGFP-expressing cell lines, the level of eGFP was determined via Western blot analyses with β-actin serving as loading control.