DKK1 and sarcopenia: Finally, administration of verteporfin improved muscle atrophy in (P)RR‐Tg mice via direct inhibition of YAP signaling (Figure 6k,l), without affecting ABC and endogenous DKK1 (Figure 6m), whereas in aged WT mice, administration of verteporfin suppressed the expression of sarcopenia‐related genes (Figure S5D).