We investigated CHO signaling events in a comparative expression and phospho proteomics approach of recombinant mAb producing XL99 cell line and according parental cells. First, on proteomic level differences between producer and parental cells were evaluated by label-free quantification of proteins at exponential growth. Next, a SILAC-based phosphoproteomic investigation was used to elucidate differential phosphorylation events following IGF treatment as well as differences between two producer cell lines and the parental cells.