Additionally, we observed the activated C3 fragments; C3b (182 kDa), C3c (145 kDa), and iC3bα (63 kDa) in the ROP vitreous under non-reducing conditions as confirmed by mass spectrometry (data not shown here), but not in the controls (Figure 1B), suggesting a higher activation of C3 in ROP. Here, C3 is linked to retinopathy of prematurity.