Figure 5.

LiCl stimulates the release of a cell death-mediating factor. (A) U2OS cells were treated with 50 mM LiCl. After 24 hours, the medium was replaced and cells were incubated for further 8, 16, 24 or 36 hours. Cells were harvested and cell lysates were prepared (LiCl). The conditioned medium from these cells was collected after 8, 16, 24 or 36 hours and transferred to untreated U2OS cells. Thereafter, these cells were incubated for an additional 24 hours. Cell lysates were prepared and 50 μg of protein were separated on a 15% SDS-PAGE gel. Proteins were transferred onto a PVDF membrane and probed with an antibody directed against cleaved Caspase-3, and against PCNA for loading control. (B) U2OS cells were irradiated with 30 J/m² UVC. After 24 hours, conditioned medium was collected and transferred onto fresh U2OS cells. The cells were harvested ("0") or incubated for a further 24 hours or 36 hours. Cells that received the conditioned medium were harvested immediately ("0") or incubated for further 24 or 36 hours. Cell lysates were prepared and 50 μg of protein were separated on a 15% SDS-PAGE gel. Proteins were transferred onto a PVDF membrane and probed with an antibody directed against cleaved Caspase-3, and against PCNA for loading control.