To monitor the behaviour of the different cell types, the heart muscle cells were furthermore
altered by genetic engineering in such a way that cells from the atrium and the ventricle lit up differently.
These GEMM - ESCs, with often multiple modified alleles, form the basis for further
genetic engineering either
by Flp - recombinase mediated integration, gene targeting or Crispr / Cas9 to allow for the evaluation of
altered target gene expression in a spontaneous tumor model.