However, further research is needed to determine if changes in CYP3A5 expression occur in the human respiratory tissue similar to A549 cells, the precise mechanism by which this process occurs, and whether changes in the local metabolism of glucocorticoids by CYP3A5 ultimately impact glucocorticoid efficiency in asthma patients refractory to glucocorticoid treatment. The gene discussed is CYP3A5; the disease is asthma.