The invention discloses a bicistronic expression carrier, an expression 
system, a preparation method and an application, and belongs to the technical field of 
genetic engineering.  The 
expression vector contains the sequence of the 
nuclear matrix binding region, the sequence of the inner 
ribosome entry site and the screening marker. By inserting the 
target gene between the 
promoter and the IRES sequence, a bicis sequence of the 
target gene-IRES sequence-selection 
marker gene can be formed.  anti subsequence.  The structure of the 
expression vector is: MAR-
promoter-
target gene-IRES sequence-selection marker-PolyA-MAR.  The vector uses a 
promoter to realize the simultaneous expression of the target 
gene and the screening marker, which can reduce the false positive 
cell clones caused by the existence of different expression cassettes, improve the screening rate of positive 
cell clones, and overcome the unbalanced expression of the target 
gene and the screening marker in traditional vectors  Question: The inclusion of MAR sequences on the vector can overcome 
transgene silencing and achieve efficient and long-term expression of transgenes in host cells.