PAK1 and cancer: On the contrary, GDF15 low expression was associated with a number of pathways known to promote cancer growth and progression (Fig. 5B), such as G protein signaling pathways, Ras signaling, Hippo signaling regulation pathways, chemokine signaling pathway, RAC1/PAK1/p38/MMP2 pathway, Focal adhesion, EGF/EGFR signaling pathway, etc. We also performed GSEA with reference to Reactome knowledgebase and found similar results (Additional file 4: Figure S4A, B).