LDLR and embryonal carcinoma: The role of PCSK9 in neuronal differentiation does not seem to be mediated by the LDLR, since neuroectodermal induction with retinoic acid of P19 mouse embryonic carcinoma cells increases endogenous PCSK9 mRNA expression, without altering LDLR protein abundance nor Sterol Regulatory Element Binding Protein 2 mRNA expression levels (43).