Since both nelfinavir and tamoxifen have to be used at concentrations higher than those used to inhibit the HIV protease in HIV-infected persons or the oestrogen receptor in hormone receptor-positive breast cancer patients, however, care has to be taken that no unexpected adverse effects occur - especially when both drugs, although displaying moderate and tolerable adverse effects as single agents, are combined. The gene discussed is NR4A1; the disease is breast cancer.