. . . . . . . "HIV-1 MA increases phosphorylation and the DNA-binding activity of CREB and c-Myc through activation of the cAMP/PKA and MEK/ERK signaling pathways. Both signaling pathways are synergistically activated upon co-stimulation through the CD19 receptor" . "HIV-1 Matrix impairs proliferation of normal lymphocytes in vitro by inducing the activity of the inhibitory protein kinase A (PKA)" . "Protein kinase A (PKA) has been shown to phosphorylate HIV-1 Matrix in vitro" . "activates" . "phosphorylated by" .