In addition, grassystatin F was shown to inhibit the cleavage of cystatin C and plasminogen activator inhibitor type-1 (PAI-1) via its inhibition on cathepsin D. Cystatin C and PAI-1 are involved in the downstream activation of cysteine cathepsins and tissue plasminogen activator (tPA), which would lead to the migration of highly aggressive triple negative breast cancer cells (MDA-MD-231) [102]. Here, CST3 is linked to triple-negative breast carcinoma.