TNFSF13B and breast cancer: Incubation of breast cancer cells with APRIL or BAFF (100 ng/ml) for at least 4 days induced a significant increase in autofluorescence, from 2.5 ± 1.2% in control (untreated) T47D cells to 5 ± 0.5% in APRIL or BAFF-treated cells and from 2 ± 0.6% in control to 4 ± 0.5% in APRIL or BAFF-treated MDA cells (Figure 3D).