The 22-1-1 antigen does not induce apoptosis in K562 cells. a) Cells were irradiated with UV-light as positive control for apoptosis, or incubated with regular non concentrated medium, or 1:4 dilution of concentrated regular medium, or concentrated MCF-7 cell culture supernatant. Apoptosis was assessed by annexin V-FITC staining. b) K562 cells were incubated with 50 μg, or 100 μg of (1) TF; (2) α-GalNAc-PAA; (3) β-GlcNAc-PAA; (4) β-GalNAc-PAA-biotin and subjected to caspase -3 and -7 activity assay. P-cells irradiated with UV; N-non treated cells.