In this series of projects of sequencing human cDNA clones which correspond to relatively long and nearly full-length transcripts, we newly determined the sequences of 80 clones, and predicted the coding sequences of the corresponding genes, named KIAA0201 to KIAA0280. Among the sequenced clones, 68 were obtained from human immature myeloid cell line KG-1 and 12 from human brain. The average size of the clones was 5.3 kb, and that of distinct ORFs in clones was 2.8 kb, corresponding to a protein of approximately 100 kDa. Computer search against the public databases indicated that the sequences of 22 genes were unrelated to any reported genes, while the remaining 58 genes carried sequences which show some similarities to known genes. Protein motifs that matched those in the PROSITE motif database were found in 25 genes and significant transmembrane domains were identified in 30 genes. Among the known genes to which significant similarity was shown, the genes that play key roles in regulation of developmental stages, apoptosis and cell-to-cell interaction were included. Taking into account of both the search data on sequence similarity and protein motifs, at least seven genes were considered to be related to transcriptional regulation and six genes to signal transduction. When the expression profiles of the cDNA clones were examined with different human tissues, about half of the clones from brain (5 of 11) showed significant tissue-specificity, while approximately 80% of the genes from KG-1 were expressed ubiquitously.