Novel calcium-independent phospholipases A2; genes encoding the same; an antibody against them; an inherent promoter or a regulator gene which comprises a base sequence occurring in intron and inducing site-specific expression in response to an external stimulus; a method of expressing a target protein in response to an external stimulus; and an organism having this gene transferred thereinto. Novel calcium-independent phospholipases A2 having an amino acid sequence represented by SEQ ID NO: 1, 3 or 5 or an amino acid sequence derived from such an amino acid sequence by the substitution, deletion or addition of one or more amino acids; a gene having a base sequence occurring in an intron and being capable of initiating RNA transcription due to an external stimulus such as a stimulus with kainic acid or an electrical stimulus; a method of regulating expression by using the gene; and an organism having the gene transferred thereinto.