In our comparison of five different experimental models of ovarian cancer, only 4 of 10 MPAS genes displayed consistent and uniform response to MEK/ERK activity modulations, and only 3 (PHLDA1, EPHA2, and DUSP4) were significantly associated with baseline ERK1/2 activity in both cell lines and patient tissue samples, thereby emphasizing the need to validate gene expression signatures for each type of pathology or condition. This evidence concerns the gene MAPK3 and ovarian cancer.