The current results suggest an impact of exercise-conditioned serum on both the phosphorylation state of protein involved in signaling pathways related to proliferation (i.e., STAT3, Akt, mTOR, p70s6k, and Erk 1/2), and supporting the Hippo tumor suppressor pathway by inhibiting Yes-Associated Protein (YAP)/PDZ-binding Motif (TAZ) in different cancer cells [67,69,73] (Figure 1), known to be dysregulated in many cancers. Here, STAT3 is linked to cancer.