TGFB1 and systemic sclerosis: More importantly, due to the distinct solubility of Rk3 (lipophilic) and Met (hydrophilic), their co-administration in a free state fails to achieve synchronized spatial and temporal effects, significantly reducing the synergistic efficacy of Rk3/Met dual-target regulation of CXCL4 and TGF-β for SSc treatment [35,36,37].