Using stem cell‐specific medium (Pollard et al., 2009), we tested the effect of R‐Tf‐D‐LP4 cell treatment on spheroid/aggregate formation and found that the peptide attenuated their formation, in comparison with peptide‐untreated lung and breast cancer and GBM cell lines (Fig. 9B,D,F). Here, TF is linked to breast carcinoma.