PIK93 is a phenylthiazole-based inhibitor of PI4KIIIb (IC50 = 19 nM) used to evaluate the role of PI4-K isoforms in calcium signaling. [1] At a concentration of 300 nM PIK93 inhibited the p110g isoform of PI3K (Class I) was inhibited at IC50 of 16 nM, while weakly inhibiting PI3K-C2a (IC50 = 16 uM). [2] PIK93 is selective for PI4KIIIb over PI4KIIIa (EC90 = 250 nM and EC50 >10 uM, respectively) and is inactive toward type II PI4Ks. [3] PIK93 was also identified as a potent anti-poliovirus and anti-HCV agent, with EC50s of 0.14 and 1.9 uM, respectively. [4]