TGFB1 and fibrosarcoma: Interestingly, in vitro studies have shown that peptide 5a and 5a-HSA can inhibit the production of TGFβ by various by αvβ6- and/or αvβ8-positive cancer cells (i.e. single or double positive) such as 5M7101/GFP/CEA cells (αvβ6pos, αvβ8neg), TS/A mammary adenocarcinoma (αvβ6neg, αvβ8pos(low)), WEHI-164 fibrosarcoma (αvβ6neg, αvβ8pos(low)), and TRAMP-C2 prostate carcinoma (αvβ6neg, αvβ8pos).