SMAD4 and myopia: What’s more, the expression of TGF-β1 receptor and effector molecules such as Smad2/3, p-Smad2/3 (the activated form of Smad2/3) and Smad4 (the co-worker of p-Smad2/3 in transcription activation of target genes) were all elevated in the lens of human and mouse highly myopic eyes, further confirming the enhanced signaling of TGF-β1-Smad in high myopia conditions.