Figure 2.

Phorbol ester and compound F co-operate to induce and maintain differentiation of THP-1 cells. A: Compound F sensitizes THP-1 cells to PMA-induced adherence. Dose-responses of THP-1 cells to PMA were prepared in the presence of vehicle alone (squares) or 100 nM compound F(triangles). Cells were plated in RPMI medium (0.1% FCS) and harvested after 48 h. Cell numbers were determined by fluorimetric analysis of SYBR green stained plates. B: Compound F co-operates with phorbol ester in promoting differentiation of THP-1 cells. Cells were plated for 48 h in RPMI medium supplemented with 0.1% FCS and 0.5 nM PMA and a compound F dose-response performed. Results obtained were subjected to non-linear regression analysis. C: Compound F maintains the adherence of THP-1 cells in the absence of a prolonged PMA stimulus. THP-1 cells were plated in RPMI supplemented with 10% FCS and 1 nM PMA. After 48 h, the PMA was removed and replaced with either 100 nM compound F (triangles) or vehicle only (squares). At 48 h intervals up to 6 days, the number of cells remaining adherent to the culture substratum was measured by fluorimetric analysis of SYBR green stained plates and the results compared to a standard curve.