Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Enzyme | Location | Substrate | Product | Chromosome | OMIM | Porphyria |
| --- | --- | --- | --- | --- | --- | --- |
| ALA synthase | Mitochondrion | Glycine , succinyl CoA | δ-Aminolevulinic acid | 3p21.1 | 125290.0 | none |
| ALA dehydratase | Cytosol | δ-Aminolevulinic acid | Porphobilinogen | 9q34 | 125270.0 | ALA-Dehydratase deficiency |
| PBG deaminase | Cytosol | Porphobilinogen | Hydroxymethyl bilane | 11q23.3 | 176000.0 | acute intermittent porphyria |
| Uroporphyrinogen III synthase | Cytosol | Hydroxymethyl bilane | Uroporphyrinogen III | 10q25.2-q26.3 | 606938.0 | congenital erythropoietic porphyria |
| Uroporphyrinogen III decarboxylase | Cytosol | Uroporphyrinogen III | Coproporphyrinogen III | 1p34 | 176100.0 | porphyria cutanea tarda |
| Coproporphyrinogen III oxidase | Mitochondrion | Coproporphyrinogen III | Protoporphyrinogen IX | 3q12 | 121300.0 | coproporphyria |
| Protoporphyrinogen oxidase | Mitochondrion | Protoporphyrinogen IX | Protoporphyrin IX | 1q22 | 600923.0 | variegate porphyria |
| Ferrochelatase | Mitochondrion | Protoporphyrin IX | Heme | 18q21.3 | 177000.0 | erythropoietic protoporphyria |
Question:
What is protoporphyrin ix's substrate?
Answer:
Protoporphyrinogen IX