RNASE1 and neoplasm: Interestingly, pre-incubation of the coculture system between PBMCs or primary T cells and BT-549-αCD3 tumor cells with the recombinant extracellular domain of EphA4 (His-A4), which can neutralize EphA4 ligands such as RNase1, significantly decreased RNase1-mediated killing ability towards tumor cells (Figure 6D and 6E).