ACTA1 and invasive ductal breast carcinoma: We also observed the development of a large, poorly differentiated and invasive cytokeratin positive/vimentin negative ductal adenocarcinoma (sarcomatoid) tumor with a significant BMDC population (Figure 4A, 4B), which included an extensive donor derived inflammatory infiltrate, demonstrated using FISH for the Y-chromosome (Y-FISH; Figure 4C), as well as bone marrow derived activated pancreatic stellate cells (Figure 4D), visualized by co-immunofluorescence of GFP with αSMA (Figure 4D).