GCA and rheumatoid arthritis: Using this method, we find that a red fluorescent signal indicating such very close proximity was obtained in neutrophils from patients with RA (Fig. 4A) or healthy controls (Fig. 4B) for PAD4 in combination with MYH9, MYL6, STOM, GCA, and NCF1 (as a positive control), while a negative control consisting of only anti-PAD4 was entirely devoid of any signal.