Problem:
I was reading this paper related to use of gene expressions for predicting the drug response. I have this confusion, the paper has used PCA on the covariance matrix formed by the genes to get what is called the background network as they say.
I don't know the essence of background in this case. I know PCA gives us components which preserves the greatest variance and used for dimension reduction.
Question : What they mean by background network. Is it pathways ? Please explain in detail.