Mouse Embryonic Kidney Fibroblast. As described in Lingenfelter et al., 1998 (Nat Genet. 1998 18:212-3) and Yang et al., 2010 (Genome Res. 2010 20:614-22), PATSKI is a female interspecific mouse fibroblast that was derived from the embryonic kidney of an M.spretus x C57BL/6J hybrid mouse such that the C57Bl/6J X chromosome (maternal) is always the inactive X. This is an adherent cell line.