SKP2 and retinoblastoma: Mechanistically, TRβ2 promotes SKP2 expression and simultaneously prevents its degradation via the EMI1/FBXO5 pathway, ensuring sustained SKP2 activity as an E3 ubiquitin ligase that targets key cell cycle inhibitors such as p27 and p130 for degradation [313], thereby driving cell cycle progression and supporting retinoblastoma cell proliferation [314].