HK2 and rheumatoid arthritis: However, our results demonstrated that the expression of key enzymes such as glucose transporter type 1 (GLUT1) and HK2 in RA-CD4+ T cells were higher than in HC-CD4+ T cells (Figures S3B, C), although there was no significant difference in lactate dehydrogenase (LDH) expression (Figure S3D).