Significantly higher uptake of [18F]FB-IL-2 was observed in MC38 tumours compared to CT26 tumours (Figure 5B), potentially due to phenotypic differences in the tumour types, as MC38 tumours are associated with a microsatellite instability-high (MSI-high) phenotype compared to the MSI-low CT26 tumours. Here, IL2 is linked to neoplasm.