The expression levels of CPS1, CYP2D6 and CYP3A4 proteins were significantly lower in the 43d M(+) cell group compared to the 1d M(+) cell group, suggesting that the extent of CPS1, CYP2D6, and CYP3A4 inhibition was related to the length of infection. The gene discussed is CYP3A4; the disease is infection.