Members of the protein kinase C (PKC) family play a key regulatory role in a
variety of cellular functions including cell growth and differentiation, gene
expression, hormone secretion and membrane function. PKCs were originally
identified as serine/threonine protein kinases whose activity was dependent
on calcium and phospholipids. Diacylglycerols (DAG) and tumor promoting
phorbol esters bind to and activate PKC. PKCs can be subdivided into many
different isoforms (α, βI, βII, γ, δ, ε, ζ, η, θ, ι, λ, μ and ν). Patterns of expression
for each PKC isoform differ among tissues and PKC family members
exhibit clear differences in their cofactor dependencies.