Summary of the three methods used to determine the human P450s involved in atRA metabolism
| Method | P450s Involved | |||
|---|---|---|---|---|
| 4-OH-RA | 4-oxo-RA | 18-OH-RA | 5,6-epoxy-RA | |
| Correlation of activity | 2B6, 2C8, 3A4/5, 2A6 | 2B6, 2C8, 3A4/5, 2A6 | 2C8, 2B6, 2A6 | 2B6, 2A6, 3A4/5 |
| Lymphoblast-expressed P450s | 3A7, 3A5, 2C18, 2C8, 3A4, 2C9 | nd | 4A11, 3A7, 1A1, 2C9, 2C8, 3A5, 3A4, 2C18 | nd |
| 293 Cells transfected with a single P450 | 3A7, 1A1, 2C8, 2C9, 1A2, 3A4 | 1A1, 3A7, 2C8, 1A2 | 3A7, 1A1, 2C8 | nd |
nd, not detected. In our HPLC conditions, the limit of detection was 2 pmol for 4-oxo-RA.