A later study using pheochromocytoma (PC)12 cells and SLC6A17-tranfected Chinese hamster ovary (CHO) cells found that SLC6A17 could transport four amino acids (AA): proline (Pro), glycine (Gly), leucine (Leu), and alanine (Ala) (Parra et al., 2008). The gene discussed is SLC6A17; the disease is pheochromocytoma.