CLOCK and cancer: Surprisingly, although progesterone receptors are expressed in the oviduct as well and have been implicated in the carcinogenesis and mifepristone-mediated prevention of cancers in this organ16, compared to the cervix, the mitotic clock in the oviduct is substantially less informative in terms of mammary gland cancer and PRBS methylation is not at all an indicator of cancer formation in this tissue.