FPR1 and myeloid leukemia: Cofilin/Slingshot/Profilin/RHGEF2/PRKAR1A. The analysis of the response of the myeloid leukaemia cell line PLB-985 to the chemoattractant fMLF (receptor FPR1) showed that the knocking down of the actin-binding proteins cofilin, the cofilin phosphatase slingshot, the cytoskeletal regular profilin, and the Protein Kinase CAMP-Dependent Type I Regulatory Subunit Alpha (PRKAR1A) led in all cases to inhibition of the motility of the cells.