Phosphatidylinositol 3-kinase (PI3K) catalyzes the phosphorylation of the 3' hydroxyl position of PIs to produce the second messengers PtdIns-(3,4)-P2 and PtdIns-(3,4,5)-P3. PI3Kα, β, and δ are class 1A enzymes composed of p110 and p85 subunits, whereas PI3Kγ is a class 1B PI3K composed of a p110 catalytic subunit and a p101 or p84 regulatory subunit. PI3Kα inhibitor 2 is a selective inhibitor of PI3Kα with IC50 values of 2, 16, 660, and 220 nM for the α, β, γ, and 2Cβ isoforms, respectively. It inhibits PKA, KDR, PKCα, and cyclin E/Cdk2 significantly less effectively (IC50 = 91, 3.4, 466, and 28 μM, respectively). PI3Kα inhibitor 2 inhibits A375 melanoma cell proliferation with an IC50 value of 580 nM.
Cytochalasin D is an actin inhibitor, the removal of actin stress fibers is crucial for the chondrogenic differentiation. It may be an inhibitor of some fertilization processes such as sperm penetration or sperm head decondensation. Cytochalasin D inhibit