TNF and neoplasm: For these experiments, NK cells were grown in co-cultures with fibroblasts as before, then collected, and employed against the tumor cell line K562 (4 h, 37°C), followed by fixation, permeabilization, and staining with antibody-markers against cytokines IFN-γ, TNF-α, and cytolytic enzymes perforin and granzyme B. Our results indicate that intracellular levels of granzyme B were slightly elevated in NK cells grown in the presence of iCAFs/CAFs rather than NFs, but the differences were not significant (Figure 5A).