L-BPA and its F-18-labeled PET probe L-18F-FBPA [7–12] are transported into tumor cells through L-type amino acid transporter 1 (LAT1) [11–13] and amino acid transporter B0,+ (ATB0,+) [13], both of which are strongly upregulated in tumor cells [13, 14]. The gene discussed is SLC6A14; the disease is neoplasm.