Breast invasive ductal carcinoma. (a-f) Histology and expression of caspase-3 by immunoperoxidase. (a-b) Untreated tumor demonstrating rare islands of cohesive neoplastic cells (black arrow), H&E at 20× and 40×, respectively. (d-e) Treated tumor demonstrating numerous islands and cords of neoplastic cells with a preserved cellular cohesion (black arrow), H&E at 20× and 40×, respectively. (c) Untreated tumor demonstrating rare residual neoplastic cells (black arrow) with rare staining for caspase-3 in ~1% of neoplastic cells compared to ~3% in treated tumor (f), immunoperoxidase (IP), 40×. (g-h) HPLC runs of intracellular caspase-3 activity in treated and untreated tumor. The AMC peak (retention time, ~4.4 min) in treated tumor was blocked by the pancaspase inhibitor zVAD, confirming the cleavage of Ac-DEVD-AMC was mediated by caspases. (i) Cellular respiration, measured immediately on tumor arrival to the laboratory to affirm viability.