Effect of TPO on the proliferation of LEC. LEC-1 (A12 clone) were seeded in 96-wells at 5,000 cells/well in serum-free conditions. Different concentrations of mTPO were added to the cultures. After 48 hours, the proliferation of LEC-1 was assayed using a colorimetric method (see Materials and Methods). The absorbance of the reaction was read at 490 nm. The results are expressed as the means ± SE. Results are representative of three separate experiments. The increase in proliferation was statistically significant for TPO at 4,000 U/mL with respect to the control (*, P ≤ .05). Similar results were observed with C7 clone.