MKI67 and neoplasm: The NETtest is a liquid biopsy test which analyzes the expression by RNA of a panel of 51 specific genes linked to key biological processes in NETs, such as cell proliferation (e.g., Ki67), neuroendocrine differentiation (e.g., SSTR5, TPH1, VMAT1), and tumor signaling (e.g., BRAF, KRAS, RAF1) [37].