Expression of SCP-1 analyzed by RT-PCR. SCP-1 expression in normal tissues is restricted to testis. Lanes: 1, PBMCs; 2, mitogen-stimulated PBMCs; 3, breast; 4, brain; 5, liver; 6, spleen; 7, testis; 8, genomic DNA control; 9, skeletal muscle; 10, kidney; 11, lung. In contrast SCP-1 transcripts are detectable with various frequencies in fresh tumor specimens, as shown for selected breast cancer and glioma samples.