Transgenic construct used as a control in a study of pairing-sensitive repression (PSR). Generated by inserting a 4 kb PstI fragment from upstream of ph-p (nucleotides 70,027 to 66,143 of AE003423) into pCaSpeR4 (which contains the w+mC minigene). In addition, a 4kb fragment containing the lacZ gene has been inserted to separate the ph-p fragment from the w+mC promoter