MYC and Miyoshi myopathy: It was therefore surprising that neither in MM cell lines engineered for doxycycline-inducible HUWE1 knockdown nor in the MYC-overexpressing subline U266-MYC, moderate to strong HUWE1 depletion had any discernible effects on the expression levels of MYC target genes, nor on MIZ protein, an inhibitor of MYC activity.