IFNG and melanoma: MelRM and SKMel28 cells, known to be IFN-γ inducible for PD-L1 expression [25] as well as NM176 melanoma cells without previously reported data regarding PD-L1 inducibility, were spiked into healthy donor blood and recovered using the melanoma CTC isolation protocol after room temperature storage for 0, 24 or 48 hours.