ACTA1 and breast cancer: As breast xenografts showed reduced activity in the microenvironment, we analyzed for changes in biomarker expression for fibroblasts (α-SMA and FSP1) and angiogenesis (VWF), and M2 macrophages (arginase-I), which correlates with fibroblast accumulation in breast cancers.43 Immunostaining revealed alterations in α-SMA and FSP1 fibroblast biomarker expression among groups.