GJA1 and ischemia: Moreover, although we had hypothesized that Cx43 would show ischemia resistance in the transgenic cardiomyocytes, both WT and Cx43-S3E hPSC-CMs showed a significant reduction in total Cx43 expression relative to their baseline counterparts following ischemia (to 0.68 ± 0.1 and 0.42 ± 0.05-fold of baseline expression, respectively).