CYP19A1 and neoplasm: (2022) designed Ru(II) photocages conjugated to potent inhibitors of cytochrome P450 aromatase (CYP19A1), an enzyme critical for estrogen‐mediated tumor proliferation.[123] Upon illumination at 660 nm, the inhibitor ligand was photoreleased and coordinated directly with CYP19A1's iron‐heme center, effectively suppressing its catalytic activity at picomolar concentrations.