A series of plasmids was assembled expressing GST-fusion proteins containing the ARID regions of representative members of ARID subfamilies. The MRF2 fusion protein is the product of pMRF2-GST, which was constructed by ligating a BamHI/SalI restriction fragment from the insert of plasmid MRF2pQE30 [(13); kindly provided by Yuan Chen at the Beckman Institute, City of Hope, Duarte, CA] into the pGEX4T vector (Pharmacia Biotech). A construct containing the ARID domain of human RBP1, called GST–ARID (19), was provided Dr Philip Branton (McGill University, Montreal, Canada). The ARID2 sequence was generated by RT–PCR from HepG2 cells using oligonucleotides ARID2-F (5′-ATAATGGCAAACTCGACGGGGAAG) and ARID2-R (5′-CACCCCGGCATTAGCAAGTAGTAA) to yield a 630 bp fragment that encodes amino acids 1–209 according to accession number XP_350876. The fragment was cloned into pCR2.1-TOPO vector (Invitrogen) to make ARID2–TOPO. The EcoRI fragment of ARID2–TOPO was sub-cloned into the EcoRI site of pGEX-4T1 (Pharmacia Biotech) to make pARID2-pGEX. The PLU-1 sequence was generated by RT–PCR from MCF-7 cells using oligonucleotides PLU-1 For (5′-TTCGCGGACCCCTTCGCTTTCA) and PLU-1 Rev short (5′-AATATTCATGGCCTCTGCTCTC). The reaction generated a 597 bp fragment extending from nucleotide 213 to 810
