Alteration in Proteins Processing Pathway - Genetic manipulation may also be used at the post translational level (after the protein synthesis is over) to increase the yield of a product Low yields of a human tissue plasminogen activator (tPA, used for heart diseases) is attributed to its association with GRP78 in rough endoplasmic reticulum of CHO cells. (GRP78 is a 78-kD glucose regulated stress response protein).

It has been shown that coexpression of an antisense GRP78 message (due to cloned antisense RNA sequence) resulted in smaller quantities of GRP78 and faster tPA secretion.