Generation of mice deficient in ARID1B. (A) Mice harboring KOF Arid1b allele were initially produced and subsequently crossed with transgenic mice expressing either FLP recombinase or Cre-recombinase as depicted in the schematic. Mice with floxed Arid1b allele were injected with poly(I:C) to induce its deletion in a hematopoietic system–specific manner. (B) Polymerase chain reaction analysis to detect deletion of Arid1b alleles (exon 5) in BM leukocytes, splenocytes, and thymocytes of Arid1b^f/f;Mx1-Cre⁺ and Arid1b^f/f;Mx1-Cre⁻ mice 16 weeks after poly(I:C) injection. Δ, deleted allele.