5′ tRNA halves are also present in human serum and leukocytes, but not in EDTA plasma. RNAs extracted from human leukocytes, 0.4 ml of human serum, or EDTA-collected plasma. The northern blot was hybridized to a 32P 5′-end labeled oligonucleotide probe complementary to the 5′ end of tRNA-Gly-GCC. The positions of full length tRNAs and tRNA halves are indicated on the right. DM: decade markers.