C LAPTM4B selectively associates with PIPKIγi5. Top: schematic diagram of four PIPKI isoforms. Bottom: Myc‐tagged PIPKIγi5 was immunoprecipitated from HEK293 cells expressing Flag‐tagged LAPTM4B and each isoform of PIPKI, followed by immunoblotting to examine the co‐immunoprecipitatedLAPTM4B. 