text: Research has demonstrated that overexpression of CRBP-I increases the ability of RBP-ROH complex to phosphorylate STRA6 and, later, JAK2 and STAT5.  Suppressing CRBP-I, on the other hand, led to decreased ability of RBP-ROH complex to phosphorylate STRA6 and signaling components.  Similarly, reducing the expression of LRAT also decreased the ability of RBP-ROH complex to phosphorylate JAK2 and STAT5. Therefore, both CRBP-I and LRAT are necessary for the STRA6 signaling cascade upon the binding and transport of retinol.  JAK2 is also conversely responsible for the activation of STRA6, after which apo-CRBP-I is recruited to the intercellular CBL of STRA6 and vitamin A might be transferred by the receptor to CRBP-I. Thus, both STRA6 signaling and STRA6 transport of vitamin A are dependent upon each other.  Uptake of retinol is required for STRA6 signaling and JAK2 activation of STRA6 is necessary for retinol uptake.