TPO mRNA expression in murine LEC-1. RT-PCR was performed on 1 μg total RNA obtained from A12 and C7 LEC-1 clones. Reverse-transcription and amplification were performed as described in Materials and Methods with the primers specific for TPO. Constitutive expression for TPO was detected in A12 and C7 LEC-1 clones. 1: Molecular markers; 2: negative control (PCR reaction without RNA template); 3: internal control, β-actin; 4: A12 clone; 5: C7 clone.