Medical Sciences. In the article "t(11;22)(q23;q11.2) in acute myeloid leukemia of infant twins fuses MLL with hCDCrel, a cell division cycle gene in the genomic region of deletion in DiGeorge and velocardiofacial syndromes" by Maureen D. Megonigal, Eric F. Rappaport, Douglas H. Jones, Terrence M. Williams, Brian D. Lovett, Kara M. Kelly, Paul H. Lerou, Thomas Moulton, Marcia L. Budarf, and Carolyn A. Felix, which appeared in number 11, May 26, 1998, of Proc. Natl. Acad. Sci. USA (95, pp. 6413-6418), the authors wish to note the following corrections. On page 6414, column 2, line 4, the text should read: "The 24-l ligation reaction mixture contained 0.5 g" not "0.05 g" as printed. Also, on page 6415, column 1, line 56, the text should read: "AmpliTaq DNA polymerase, all four dNTPs (each at 200 M)" not "(each at 250 M)" as printed.Medical Sciences. In the article "Potent inhibition of human immunodeficiency virus type 1 replication by an intracellular anti-Rev single-chain antibody" by Lingxun Duan, Omar Bagasra, Mark A. Laughlin, Joseph W. Oakes, and Roger J. Pomerantz, which appeared in number 11, May 24, 1994, of Proc. Natl. Acad. Sci. USA (91, 5075-5079), the undersigned authors wish to note the following: "The sequence of the heavy chain of the D8 anti-Rev single chain variable fragment (SFv) has been reanalyzed and found to be not what was reported in the article. It is likely that the coding DNA was derived from the fusion partner cell line used to make the original D8 hybridoma, and not from the heavy chain gene expressed by the B cell precursor to this hybridoma. There is a deletion in the framework region 3 (FR3) leading to a framehsift in CDR3 and downstream regions of the heavy chain gene. Individual nucleotide differences make this sequence very close to that described [Thammana, P. (1994)
