The embodiments of the present invention are directed to discrete,
cis-acting regulatory elements that include a barrier element, an
insulating element, a silencing element, and matrix attachment regions
("MARs"). Additional embodiments of the present invention are directed to
nucleic acid molecules that are useful for facilitating stable transgene
expression within a chromatin environment. Additional embodiments of the
present invention are directed to recombinant expression vectors
including nucleic acid molecules of the present invention that can be
incorporated into artificial chromosomes, eukaryotic cell-lines,
non-human transgenic animals, and transgenic plants, to improve
recombinant protein production in a broad range of eukaryotic hosts, and
pharmaceutical compositions including nucleic acid molecules of the
present invention that are also useful for gene therapy in the treatment
of various genetic diseases.