Which is used in production of insulin by genetic engineering

Which one of used in the production of insulin by genetic engineering ?

Which one of used in the production of insulin by genetic engineering ?

Raju is a diabetic patient who takes insulin injections regularly. The insulin used by such patients is produced by genetically engineered organisms. Write the different steps involved in the production of insulin by genetic engineering.

The step that proved to be the main challenging obstacle in the production of human insulin by genetic engineering is :

The step that proved to be the main challenging obstacle in the production of human insulin by genetic engineering is :

Which step proved to be the main challenging obstacle in the production of human insulin by genetic engineering ?

Which step proved to be the main challenging obstacle in the production of human insulin by genetic engineering?

Which step proved to be the main challenging obstacle in the production of human insulin by genetic engineering?

Which step proved to be the main challenging obstacle in the production of human insulin by genetic engineering?