ITGB1 and breast adenocarcinoma: In tumor samples from human breast adenocarcinoma, Costa et al. identified four subtypes of CAFs, designated CAF-S1 to CAF-S4, based on the expression of six markers, including integrin β1 (ITGB1, a.k.a. CD29), αFAP, PDGFRβ, FSP-1, α-SMA and caveolin 1 (Cav1).