ESCO2 and Roberts-SC phocomelia syndrome: To be able to study the role of ESCO2 in sister chromatid cohesion and DNA damage response, SV40 immortalized, ESCO2-deficient fibroblasts from a Roberts syndrome patient (VU1199-F SV40) were stably transfected with cDNA constructs encoding either V5- or GFP-tagged ESCO2 protein.