JWA, a cytoskeleton associated gene, was primarily found to be regulated by all trans-retinoic acid (ATRA), 13 cis-retinoic acid (13 cis-RA) and 12-tetradecanoylphorbol-13-acetate (TPA). Our previous data showed that JWA might be involved in both cellular differentiation and apoptosis induced by several chemicals. In this study, we addressed the possible mechanism of JWA in the regulation of cell differentiation and apoptosis in NB4, a human acute promyelocytic leukemia cell line. CD11b/CD33 expression and cell cycle were analyzed for detecting of cell differentiation and apoptosis. Both reverse-transcription polymerase chain reaction (RT-PCR) and Western blot assays were used for understanding the expressions of JWA. The results showed that under the indicated concentrations ATRA (10⁻⁶ mol/L) and AS₂O₃ (10⁻⁶ mol/L) induced cell differentiation and apoptosis separately; while both 4HPR (10⁻⁶ mol/L) and TPA (10⁻⁷ mol/L) showed dual-directional effects on NB4 cells, they not only trigger cells’ differentiation but also induce cells apoptosis at the same time. All chemicals up-regulated JWA expression whatever they trigger cells either differentiation or apoptosis; however, it seems that the chemicals have no effect on PML/RARα in the treated NB4 cells. Anti-sense JWA oligonucleotide could partially block the ability of TPA in inducing cell differentiation and apoptosis via direct signal pathway. Interestingly, a high molecular weight JWA protein (JWAF) was identified only in de novo primary APL cells and it was also responsible for ATRA treatment. It raises questions of whether the JWAF is a novel APL specific marker and, how it was involved in the known mechanism of APL.