For example, progesterone membrane component 1, which is abundant in many brain regions (4) and has been proposed to mediate progesterone neuroprotective actions (55), acts as an adaptor protein for mPRα in breast cancer cells, by coupling to mPRα and facilitating its transport to the cell surface where it mediates its membrane receptor functions (56). The gene discussed is PAQR7; the disease is breast carcinoma.