A cell-permeable morpholino-thienopyrimidine compound that acts as a potent and isoform-selective inhibitor of PI 3-Ks (IC₅₀ = 2 nM, 16 nM, 660 nM, and 220 nM for p110a, p110b p110g, and PI 3-K C2b, respectively) and inhibits non-PI 3-K kinases only at much higher concentrations (IC₅₀≥3.4 mM for Cdk2/E, KDR, PKA, and PKCa). Shown to inhibit cell proliferation (IC₅₀ = 580 nM) and serum-stimulated Akt phosphorylation (IC₅₀ <3 mM) in A375 melanoma cells.