NUBPL and cancer: In addition to catalytic subunits, assembly factors also contribute to the functional integrity of Complex I, NUBPL (also referred to as IND1 or huInd1) is a mitochondrial assembly protein responsible for incorporating iron–sulfur clusters into Complex I. Aberrant NUBPL expression has been associated with cancer progression, particularly in colorectal carcinoma, where it is significantly upregulated in tumors, especially in metastatic lesions.