PTK2 and breast cancer: Under chronic stress, corticotropin-releasing factor (CRF) released by the hypothalamus has been found to promote breast cancer cell invasion and metastasis through mechanisms involving FAK phosphorylation, actin polymerization, and prostaglandin production.171 β-Adrenergic signaling activated by chronic psychological stress has been shown to not only activate prometastatic pathways within breast cancer cells but also participate in the construction of premetastatic niches.