CD4 and infection: While all three isomers of RyRs were detected in the HIV-infected and uninfected CD4 + T-cells, the expression of RyR1 was the same or very slightly downregulated (not significant) in HIV-infected cells compared to the uninfected control cells; and both RyR2 and RyR3 were upregulated post-HIV-infection (Fig. 1).