When searching for Drosophila fos homologs, FlyBase presently indicates the existence of two unannotated genes, fos84E and fos93F, beyond the well characterized kayak gene. The two unannotated homologs were originally identified by Kurzik-Dumke et al., 1993, D. I. S. 72: 139, Genetic mapping of a new Drosophila fos-related sequence isolated via PCR technology using mammalian c-fos specific primers. These authors have also deposited the DNA sequences obtained from the two PCR fragments that they have amplified by a pair of primers designed based on conserved fos sequences. These DNA sequences (GenBank: Z16407.1, clone pdf800; GenBank: Z16405.1) have not yet been used by FlyBase for a further evaluation of the two proposed fos-related Drosophila genes. However, BLAST searches with these sequences reveal the following:
   1. The sequence corresponding to the proposed gene fos93F (Z16407.1) hits the intergenic region between CG31176 and Sfp93 (which includes CR44096 and CR43096) in polytene region 93. FlyBase does not provide evidence that these sequences are being transcribed, consistent with the results of the Northern analysis by Kurzik-Dumke et al. (1993).
   2. The sequence corresponding to the proposed gene fos84E (Z16405.1) hits a region within the gene Piezo (a region annotated as part of two alternative exons and an intervening intron) in polytene region 28F1.
   To prevent future confusion of FlyBase users concerning fos homologs in the Drosophila genome, it would be preferable to amend this information, or - even better - eliminate the "genes" fos84E and fos93F from FlyBase.