For example, in a study by Li et al., the authors looked at the presence of exosomal claudin-4, a tight-junction protein, and found that EVs in 32 of 63 plasma samples from ovarian cancer patients were positive for this protein, while only 1 of 50 samples from the healthy control group exhibited claudin-4 positive exosomes. This evidence concerns the gene CLDN4 and ovarian cancer.